Woman's guilt will get you nowhere.
We know you're sexually attracted to him so...
Ask yourself a few simple questions:
1. Can you see him in a relationship with you?
2. Do you think he was avoiding you because of any other reason than the way things happened?
3. Did you find yourself completely comfortable with him while he was with you?
If you can answer "Yes" to any of these questions, then I would think it would be most complimentary to him if you got in touch with him and asked him out. A person has to examine when he/she feels right about a situation and take every opportinity to take chances. There is no harm done in trying and life is VERY short.
Forget about the "girl-chasing-guy is wrong" thing. It's a different world now. Find out if it's the right thing to do by trying to ask him out rather than wondering later over an over what would happen.
If you get a "no", then you've closed the gap. Next time, you'll feel more confident about reaching out to another guy and not sit by in insecurity. It will be good for you. Trust me.