Stuck in my head

Ever get a song stuck in your head? Or just have the odd bit of music pop into your thoughts?

For some reason I generally have "Favorite Things" and "Raindrops Keep Fallin' On My Head" running through my mind, at totally random times, for no apparent reason.

Since "Favorite Things" starts with "Raindrops on roses and whiskers on kittens" rain is definitely a connection between the two songs...

But still, I'm not thinking about rain, wanting it to start or stop, and one or the other just starts up. They're not on my iTunes or iPod so I'm not hearing them there and recalling them later. They're not played on the radion stations I listen to in the car or on any CDs I own. So why? A little disconcerting...