I woke up at about 3am to this message on my phone. It was on a charger at the time. In addition it said "try again in 1min". I was not in the mindset to wait 1 minute at 3 am so i went back to sleep and when I woke up at 8am, all was fine.
After doing some research it seems that the leading cause of this issue is too many wrong password attempts. I doubt that i tried the password in my sleep, so what could be the real issue? After 10 wrong attempts, my phone should wipe itself and there was no sign of that.
I did notice that the slide bar was flashing "slide to unlock" in different languages like it does when you firt set up the phone or after a major update. Any thoughts?
Added (1). Thats is definitely a possibility in the apartment i'm in now. The power seems to fluctuate all the time and The phone charger is one of the few Items that is not on a power strip. I have noticed since I have moved in that the gfi outlets trip all the time.