What do you guys think?

I'm 20 years old, 3 weeks ago, i saw this girl at the gym that i thought was gorgeous and i realized i used to go to school with her back in grammar school. She was one year younger than me and i didnt know her at all back in schoool but i knew of her. So i asked her if she went to Our Lady of the Valley (the school i went to) and she said yea i did. So I got her sn, and for about 4 days straight she IMed me every day, left me facebook comments, and told me repeatedly she wanted to hang out with me, and even sent me her number without me even asking for it. So we went to get ice cream and she came back to my house and it was a good night cuz we had fun, I went to kiss her and after i kissed her once on the lips, she just kinda turned her head. I didn't act mad or ask what her problem was, yet ever since that night she hasn't contacted me once, whether it be on the phone or on AIM, and everytime i try to talk to her she either ignores me or says she has to go right away, I DONT GET ITT