Hmmm, very odd...
I noticed another weird music bug back in 4.2 that may be related? A known iPhone OS bug on older phones is that sometimes the music player will get stuck on the lock screen even if there's no music playing, as long as the music playing app is running on the phone. (Article here:
https://appletoolbox.com/music-app-stuck-lock-screen/ ) The only way to get rid of the stuck Music widget was to identify and close the app responsible. In this case, the app was SGM, which is odd since it's not a music app and shouldn't have the correct permissions and such to play music while the phone is locked. Closing SGM would make it go away for a little while, but after opening the game it would come back after a little while seemingly at random ( like the weird music in the first post ). Restarting the phone had no effect. Eventually it stopped happening after a few days, which makes it even more mysterious. It slipped my mind to report it then since I couldn't grab any solid proof and I thought it might've been more OS related than a bug with the game, but if odd music related things keep happening...
Also, back in 4.2, one of the Ads I watched ignored the fact that my phone was muted / vibrate only. It only happened once, but still.
So I'm wondering if these bugs may all be related and may be related to buggy Ads, and maybe the cookies related to them that might be stored in SGM's temporary game files. ( Idk how in-game advertisements work, but I think they have something similar to cookies? I remember seeing a post after 4.2 launched where someone was complaining about something like them, but I can't seem to find it anymore. )