Mystery sort of solved. My rental manager went up to take a look to make sure everything was OK, and there was a note wedged in the door from the Sheriff’s office saying that they had responded to a 911 call, checked it out, and everything was secure.
I called the Sheriff’s office, and they said they received a 911 call, so went to check it out. I asked them which number the call came from (because the cabin is empty) and they said 925 area code, but would not tell me the number. We live in the 650 area code. They seemed to imply that it was from a 925 cell phone, made in my general area. I don’t know if they checked all the cabins in the general vicinity, and also didn’t think that they could tell where a cell phone made a 911 call from.
Anyway, no harm done, good to know my camera works and that the sheriff’s office responds. Hope all neighbors are OK.