My friend is 12, I don't know what to do.?

She's only 12 and I'm 13. We're both girls, as you can tell because I said she. I noticed that when I started to hang out with her more, she got more.. personal. I noticed mostly, she is rubbing her "chest" against me on purpose. I look down to find her trying to get really super close to me and I think trying to hold my hand even. I'm bi but it just doesn't feel right. Right now she is in Tennessee for 4-6 weeks so I don't have to worry about this but it's really starting to get to me. One time, we were on my trampoline and she took my phone, when I tried to get it back, she tackled me and got on top of me! It was so uncomfortable, the position I mean. I don't know whether to confront her or act as if everything is okay. Again, this girl is 12! Any suggestions?