For the past few weeks now the Spotify app on my iPhone 6 (iOS 9.3.3) has been closing at seemingly random times during playback (app remains open in the background but stops playing and kicks me back to the iPhone home screen). I have tried all the usual fixes -- closing and reopening app, turning phone off and back on, uninstalling and reinstalling app, etc. and nothing has worked. It might play for a few minutes or a few hours before shutting off...but for the last couple days it has been more often shutting off sooner than later. I have the premium plan.