Mimicry is a sign of attraction. That, or she has a similar background to you, and consequently has similar mannerisms. I wouldn't confront her about it. If she starts talking to you, then she probably kinda likes you. If she hardly looks at you, then she just has a similar background.
I ignore practically half the messages I get on FB and don't even think about it. So does everyone else. I don't do it to be rude, it's just a habit. We have stuff to do, and we aren't always able to reply to everyone.
So try not to think too hard about what other people are doing towards you, because they're not really thinking about it either. Its weird, I know. I used to do the same thing.
Good luck dude!