A female friend is acting weird?

I have been hanging out with this girl for a few weeks. We haven't kissed or anything, but we have held hands and snuggled a few times. I interpreted this as her liking me. This last Friday she invited me over to hang out. We got comfortable and close and I sort of just kissed her. She kissed back for a few seconds, then she said "This is dumb" and just kind of blew me off. I then told her I liked her, too which she told me she had no idea. She also implied that she didn't feel the same way about me. I would have expected her to ask me to leave, but she acted like nothing really happened and we kept snuggling like nothing happened. She even gave me a big hug when I left. I talked to her that night over Facebook and everything seemed OK. This week however, she has been completely ignoring me at school. What does this mean? I have already made it obvious that I like her, but she is giving me mixed signals. What should I do?