We had something very similar to this, but I figured it to be a static electricity issue... I couldn't find anything wrong with the programming and I sat at site for 2 days monitoring system.
The system went into night mode once when I was there, I got customer to buy a static mat for the floor under desk and a static free desktopper.
Issue never happened again.
Coincidence - maybe, but I've never heard of the issue again from that site.