Did you the leave setting on where the second screen stays on all the time? If so, I think it's a possibility that the flashlight shortcut could've been tripped. I imagine that the light could heat up the glass if it stayed on long enough. Just a thought. That sucks though!
My second screen always seems to default to the Date \ Time one when the main screen is off and I have to scroll to get to the one where the flashlight is an option. Does everybody elses second screen behave the same way? I'd be concerned about the flashlight turning on accidentally in my pocket and would prefer the default screen to stay on the date \ time one.