Naw. Language changes. People find more and more efficient ways to pass on information.
I mean, I know what you are talking about, but what’s the point of getting all bothered about it? It’s not as if you could change it. You’re only going to keep yourself annoyed if you think about it.
Also, it probably is correct usage. Remember, the original metaphor is a book called a Facebook, and everyone had one when they were books. So it still makes sense to call it your Facebook, since in essence, that’s exactly what Facebook, the company, is selling.
In any case, it’s Facebook. Who really cares?