Same issue here on my iPhone 5S running the latest iOS 10 (although it's happened since before the last major update). The quirk I notice is that it never auto-plays things from my playlist, but rather creates a radio channel (featuring The Pretty Reckless and never any other artist) and only auto-plays it when I'm trying to listen to something else. Whether it is in the car or I'm using headphones, I'll be listening to a song and then The Pretty Reckless Radio comes on, pausing the thing I was previously listening to. It should be noted that I cannot recall this ever happening while listening to music with just the built-in speaker, but there is no reason my car or headphones should be even capable of starting a radio channel.
I've disabled everything I can think of relating to Apple Music and Siri (and do not have random Siri or Voice Control errors), and it still happens - even once when I had Airplane Mode turned on...the song that was queued up was not one that I own and it didn't play, but that didn't stop it from trying.
Sometimes I'll go weeks without it happening but other times it will happen more than once while I'm listening to a single song. And I can't go back to my playlist from the lock screen, either; I have to unlock the phone, open Music, and press play manually - not ideal when you're driving down a busy highway. I don't have the same issues that others have with cars trying to autoplay, bad headphones, or random plays while hooked up to Bluetooth equipment and it never happens when I'm not using the phone (thankfully) but it is annoying.