What a coincidence! I got home last night and mine was off too! I have the same model, and this is the first time it's ever done this before.
Upon close inspection, the plastic enclosure for the GFCI is cracked, and since we've had monsoon season lately, I'm guessing water has gotten into it. I was able to press reset a few times and it finally came back on. But after my external timer clicked over, it wouldn't come back on again without more fiddling.
Since my entire circuit is GFCI protected, I'm probably just going to cut it off and put a plain plug on the cord. I had to do this with the pump, because every time the external timer kicked on, it would trip the GFCI built into the pump's cord.
I use an external timer for the pump and SWG because it gives me more flexibility as to when I want them to run.