I have only been diagnosed a couple of months and I don't really use the term Aspie but I don't find it offensive. Rosska beat me to it about the whole "gay" thing. It is the context of the use, not the word itself.

I remember after I was first diagnosed I was talking on a chatroom about "Aspie traits" and one woman was like "hmm... uh huh... that's very interesting... but erm... where is Aspie exactly?"