This happened to me. However, mine would not turn back on. Even with a hard reboot. I held the buttons for at least 30 seconds. I connected it to my computer with iTunes, nothing. Went to Apple store, guy could not get it to turn on either, until, he connected it to iTunes. Then it finally came on. Why there, and, not for me, I don't know. He ran a diagnostics, found nothing. Still, he replaced the phone thinking it may be a hardware issue and may happen again. Just a thought, a few hours prior to this happening, I set one of the default live wallpapers as my background. Probably has nothing to do with it, but that was the only thing that I had changed before it happened. Anybody else have a live wallpaper set when this happened? Or, maybe it was just a software glitch that has been fixed with the most recent update. Was running iOS 9.1 beta 2 at the time.