First off, I'll apologize for the length of this post, as it may end up being longer than I really intend, and I'll also apologize if this seems like a dumb question. I'm 24 and, sadly, not a seasoned veteran of the dating game.

I'll provide cliffs at the bottom. Fake edit: holy crap this got long. I probably owe you a beer if you read all of it.
It started around the beginning of September when eHarmony hooked me up with this amazing girl. She's 21, smart, friendly, IMHO quite pretty, and as far as I can tell, very hard-working. Currently, she's in this really hardcore master's degree program that's supposed to take only 11 months, at which point she'll have what she calls an "MSW," or a master's degree in social work (this is important). Also, based on what she's told me, it's my somewhat educated guess that she's not that experienced with dating either, and doesn't have a huge circle of actual friends she hangs out with regularly, saying the only men she sees at all on a regular basis are a couple of guys in her classes and one of her profs.
So, we BSed over AIM for a few weeks before deciding to get together for dinner at this little restaurant in her town. We scheduled that date about two weeks prior, as she had to visit her parents on the intervening weekend or something, but she'd IM me at basically every chance she got, usually apparently just wanting to talk. I took this as a good sign. The first date (Friday night) went pretty well, I thought, and we sat around talking and laughing for like an hour and a half after the check came. She
said (to my face) that she had a good time, and gave me a hug as we parted company. She was sending me instant messages within like 5 minutes of when I walked in the door and bumped my desk accidentally, causing AIM to go off of idle. I again took this as a good sign, and the next day (Saturday), when she did this again, I steered the conversation such that we made plans to meet up for dinner at this cool burrito place in my town the next day (Sunday).
Now, in the preceding weeks, she had told me on several occasions about her schoolwork, which is more or less her full time job at the moment, including about how she has midterms this week, usually in the context of telling me about what she did that day, as opposed to some nakedly obvious excuse to blow me off. In particular, she mentioned a group project that she had to work on, I think expressing frustration with one member of the group who was useless or something. Anyway, mid afternoon Sunday, I was just chilling at my computer when she sends me an IM saying she has to cancel dinner for that night in order to work on said group project. The next day, I tried to get her to reschedule, but she said "We should. I'm sorry to postpone, but I have to housesit for my parents next weekend, can we revisit that next week?" I said "Sure," told her "goodnight, and good luck with the studying," and went to bed.
I gather she's been busy preparing for midterms, as she told me she had at least one yesterday, and she put up away messages implying that's what she's doing. The thing is, though, I haven't heard from her at all since Monday night, which wouldn't bother me, except it's way out of character for this particular girl, and all the other girls I've gone out with in the last year were asking
me out again within a few days of the first date.
So here are my questions:
Is this behaviour normal? I mean, I can hardly fault this girl for applying herself, but it seems strange that her behaviour pattern would completely change like that. When I was in school, I never really changed my routine when preparing for exams, so this seems foreign, to me.
My biggest question, though, is is there any way to salvage this? I'd really like another shot with her, as I felt like we're on the same page in many different ways, and I almost never meet women I feel that way about. At the same time, though, I don't know what to make of the way she totally stopped talking to me, although she did something similar early on, before we went out, when she had some sort of medical problem and had to go home for about ten days in order to use her parents' military hospitals, and pretty much picked up right where we left off when she got back to normal.
Any thoughts? Wanna tell me I suck at life? Am I just overanalyzing? (Pretty sure that's a yes) Should I just wait till next week like she suggested before worrying?
Cliffs:
1. eHarmony hooks me up with an awesome girl who is in an apparently highly demanding master's degree program, and possibly inexperienced at dating
2. BS with her on AIM for a while - she usually initiates, seems interested and very bubbly and friendly.
3. Go out for dinner - have a good time, seems easy to get her to laugh.
4. She keeps acting interested from what I can tell; make plans saturday to get together pretty informally on Sunday night.
5. She blows me off, stops talking to me, citing school work. Excuse sounds credible, except for the fact that it's an excuse.
6. ...
7. No profit.
8. What do I do?