Funny, I might have the same issue. It came on several times, I beleive at different times of the day for us. I sent one of the kids in to investigate and turn it off. Then the next night it came on again. This time I went in and found that the alarm was on. The alarm button is easy to hit and it defaults to midnight if you don't set something different. We came home that day so have not been able to see if we are still being haunted or not but will be paying more attention to it next time we go out.
2000 F-350 Dually, 7.3, 4X4
2012 Silverback 35QB4