No you are not alone in this one at all.... Happens to me all the time... not just music but phrases, thoughst, ideas, words, numbers....get repeated in my head over and over...

My younger son was into commercials when he was young and when we went shopping he would sing the commercial song for each product in every isle that he knew and those would get stuck in my head , so that even when he wasnt with me I was singing those dang commercials when I shopped! LOL