Musical Mind

Does anyone else ever find themselves humming (or singing) a tune that they have not heard played or even mentioned recently?

Why is this?

Is it our brain subconsciously associating a particular piece of music or song to a thought we have had during the day at some point? For example, I found myself humming Shoot the Runner by Kasabian (an excellent, very catchy song, if you haven't heard it) on the way to walk this morning, despite the fact that I haven't heard that song in ages.

Nobody mentioned it to me and I hadn't seen it written anywhere either. Nobody even said the word "shoot" to me, as that might have been a trigger for it.

The only answer I can think of is that I saw someone jogging past me this morning while I was walking to the bus stop. They could technically have been classified as a runner, and although I had no intention or desire to shoot them perhaps my brain came up with this link all by itself?

The mind is a wonderful thing, but sometimes I really wonder how it works.