More of a novelty, taking advantage of the new media format.
Jimmy Buffett included a cover recording of Stephen Stills' "Treetop Flyer", hidden at the end of his "Banana Wind" CD. He added a novelty intro as well, similar to Petty's example.
I didn’t scroll down to your post before I posted mine. Sorry.
I still get a chuckle out of that. That was one of my early CDs.