Well it's up to you to decide what's right for you here..
If you like her and have a romantic interest in her then you have a couple of options..
You can either talk to her and tell her how you feel and risk possible rejection if she doesn't feel the same way..
OR You can keep it to yourself and kick yourself in the butt later on that you didn't take the risk.
IMO you can usually tell IF someone has a mutual interest in you..
I will say this.. IF this girl asks for your advice on other guys, or gives you all the 411 of who she is into (and it isn't you) then she may see you as a friend only..
Good Luck