I woke up at some time early in the morning as I sometimes do, gave the clock a funny look since something didn't seem right and peered at my phone. Which for some reason was off. Didn't remember turning it off. Turned it on and looked at time. 6:30ish. Rolled over and went back to sleep. Woke again later. Sound of schoolkids outside. Look at clock. 7am. That can't be right. Look at phone. It's off again. Turn on. It's 8:35. No alarm went off. Except normally the alarm goes even if the phone is off. Sit around for a bit looking puzzled. Look at phone again. It's off again. Unplug and turn on. Definitely time to get up.
Phone has not turned itself off again since. Alarm is definitely set on. And I don't know how I managed to change the time on the clock by an hour and a half without noticing. God knows what happened. But both at the same time is just weird.