Self-inflicted burst-pipe wound out in the shop. I unplugged one of the heaters for a portion of the shop, because the thermostat was over 20 degrees off (just figured out how to adjust it earlier today). While set at 40 F it was heating that space closer to 65 F. Was using way too much propane so I simply unplugged it. Well, that bay got below freezing for a few days, long enough to freeze the pipes in the little kitchen - I completely forgot about that else I would have turned off the water. Once I got the thermostat calibrated I plugged the unit back in, it brought the temp up to the high 30s. That was enough to thaw the water in the burst pipe and, well, wet floor. Fortunately I caught it when I went back out to the shop to do something else.
Lesson learned. At least it's a pretty cheap one.