Why did she stop talking to me?

I met a girl over the summer that just so happened to be going to the same college as me. We talked all summer long and she was so excited about getting to know me and hanging out in college. She visited me at work a few times during the summer too. Well, college came around and she invited me to her party. We had a great time, but for the next month she wouldn't talk to me. I'd call her and she wouldn't pick up or return the call, and wouldn't respons to my IMs. I finally got a hold of her and I asked if I had done something wrong. She said no, I didn't do anything wrong at all, and that she has just been too busy to talk with me. What is she trying to say?