ok I'm lost

Hey guys I'm back.

OK at the end of the school year last year and about half a month after school got out, I went out on dates with this awesome girl I always thought was out of my league. They went great, and we became fairly good friends. Well, during the summer she said we should hang out more before school starts, so we did, but I initiated everything. And at the last time we hung out she mentioned that she was going to go home and watch a movie on a saturday night. So I asked if she wanted any company, not implying anything, but she said she was really bumbed about a bounced check and that her friend was already coming over, even though she didnt really want him to.

Well I called her about 4 days later to see if she wanted to hang out but she didnt answer and never returned my message. I waited a few days for her to call, but she didnt so I just put it out of my mind, figuring if she wanted to hang out she would come by my work like she has before...she didnt.

So about a month passes and school starts again, and shes in 2 of my classes, shes never been in any single one of my classes for the entire time we went to school together. Well she doesnt talk to me anymore, she doesnt say "hi bobby" when I pass her in the halls, she hasnt spoken to me once this year, even when she has had opportunities better than last year when she would speak to me, but I have noticed her look at me a time or two in class, just like I have looked at her. I think we may actually be trying to avoid meeting eyes in class. The only positive sign I've gotten is when we passed each other in the hallway, we met eyes and she smiled, the exact same way she did for the entire last semester last year.

So my question is whats up?
Did I screwup without realising?

Or are we both just nervous? I'm not sure about this one because she is very confident and outgoing.