Taking girl's SN from her Facebook? Too creepy/stalkerish?

So this girl friend requested me and I met her just 3 days ago. She did not give me her AIM screenname, but it IS on her facebook. Is it creepy for my to add her SN without her giving it to me and then IM her with "hey whats up?" I do tease her a lot before this, so I don't want her to think I'm obsessed with her or anything.