I wonder if anyone else has had this experience which has happened to me a few times now. Being a really hot, humid morning as I topped up the dogs' water bowl, I muttered, "there you go, keep yourself alive". My mind immediately began playing the Queen track Keep Yourself Alive. It ran silently in my thought process for a while without any real concentration. A few minutes later, when working outside, the silent track had switched to Doing All Right, the second track on the album. As far as I'm aware due to various distractions which had occurred in the interim, I hadn't kept the initial track running in my mind, but the next track seemed to start at just about the correct timing. As I say, it's happened before and I'd be interested to hear if it's not unusual.
Interesting! I haven't had that experience to my (conscious) knowledge.
I think this must definitely be a thing (for me anyway). After hearing the Rick & Morty trailer for the umpteenth time, the Ace Of Spades one, I continued with the cooking and my mind drifted away from the song again. However, a couple of minutes later, I found myself at the chorus of Love Me Like A Reptile. I do think the brain continues to play the memorised album without prompting.