Do you have the rear view mirror that dims when lights hit it?
It could have been used for a remote start antenna, or if the previous owner mounted a radar detector or something else hardwired up there that instead of removing it, he just cut it.
On second thought, does the wire look like it is out of place? Have any pics of it?
You know the world is messed up when the worlds best rapper is white, the best golfer is black, the tallest man in the NBA is asian, and the girl with the highest voice is Justin Beiber.