I get this too, but I think I had a lot more of it when I wasn't on meds. I still get phrases and tunes stuck in my head all the time though. Most of yesterday it was "lazer beamz lazer beamz lazer beamz lazer beamz lazer lazer lazer beamz lazer beamz..."

However, and I'm not sure if this is related, I also have noise that's not intelligible. It makes it difficult to think because I have to think louder, sort of, and it stresses me out in the same way noises do. Not sure if noise is a good word for that.