Interesting! I hear the music, new and old, in my head. I've never thought about it in this way before though.
As an add on, I don't have perfect pitch when I hear music being played, but I've noticed that I do have perfect recall pitch when I listen to a song in my head.
For instance, I can tune my bass to concert pitch by listening to the intro of Around The World by the Chili Peppers in my head as I know that it starts with Flea hitting a big E, so I tune my open E to his by singing that note and holding it, then the rest of my strings off that once I'm in.
Is this normal? Do you recall songs in your head in the keys they are really in?