Totally get that. My brain digs up the theme song from "Today's Special" at the weirdest times. Guess our heads are just full of old commercial jingles and kids show tunes forever.
Man, it's wild how these old songs become the soundtrack to boring tasks. I'll be doing dishes and suddenly my brain's playing the full "Reading Rainbow" theme. Or I'm at the grocery store humming the "Land Before Time" song in the cereal aisle. It's like our minds use this junk to fill every quiet moment.