Why did my ex-bestfriend request to be friends with me on facebook?

[Liz]

When I moved out of state, I dropped a lot of crappy "friends". One girl, in particular was difficult to part ways with, but I didn't want to surround myself with people who only talked badly about me. Recently she sent me a request which I considered accepting... But then I remembered that she was never a good friend SO WHY WOULD SHE SEND IT?? Its hysterical to think this person would have any positive intentions. During my trips back home, I would always hear that she was talking about me... FOR NO REASON! So long story short, all I can think is that this person is trying to keep "tabs" on you. She wants to keep in the loop about whats going on just as my exfriend.
OR, she could want to reconcile.