Am I just being paranoid?

My boyfriend is from California and talks about old friends things like that all the time well one of his old buddies messaged him on facebook a couple days ago and was all "Hey do you remember me?' little miss whoever from long ago with some skanky profile pic anyways I try and shove this jealous girlfriend feeling off its just an old friend right? well I caught a glimpse of another message she sent him today saying "yeah and do you remember I had a twin sister ;)" Should I be worried at all?