While I have no idea what that is, nah, that kind of stuff is really fun. I’ve seen that kind of thing a few times, usually for humor. Gravity Falls has a bit where right before the theme kicks in Mabel says “My favorite part is the theme song.” which is really funny. And Sailor Moon uses the title song both for humor—where Usagi and Naru are auditioning for a talent show and sing it very, very poorly—as well as using it for some genuinely touching moments with Tuxedo Mask’s music box playing a somber version of it. There are also plenty of moments where the intro or outro music kicks in in the background that always heighten the scene they’re in, but that’s a little different since the music is non-diagetic.