Traveled again this week and I guess risked this again and plugged into 110v while at same airport garage. Three times now over last few days I’ve received a message that sentry mode has triggered an alarm state. The first time I called about 40 minutes later to the garage and they didn’t recall any alarms going off.
There are three states for Sentry Mode: Standby (observing and, if it's set up with a USB drive and activated, recording, but nothing interesting happening); Alert (a potential threat detected nearby); and Alarm (the threat becomes very serious, like if a window is broken; the alarm then sounds and you receive a notification on your phone). If you've set it up to record clips to a USB drive, then ten minutes of video will be saved for both Alert and Alarm states. Tesla's manual says that the car "may" send 6 seconds of recording to Tesla when an Alarm is triggered, but the manual doesn't say how to retrieve that recording.
If you're seeing notification of Alarms, then that
could mean that another car has collided with yours, that somebody has broken a window, etc. AFAIK, Alerts do not trigger notifications on your Tesla app. In my experience, Alerts are often triggered by people getting into or out of the car parked next to mine or even walking past my car; the activity is usually harmless. Some activities (like keying a car) might trigger an Alert but not an Alarm, though, despite being harmful. On the flip side, an Alarm might be real or it might be a false alarm, like an ICE vehicle backfiring near your car that the Sentry Mode code mistook for a window being broken. I recall seeing a YouTube video in which an inflatable beach ball, bounced off the car's window, triggered an Alarm but did no harm to the car. Criteria for what really constitutes a threat, much less actual damage to the car, are tricky to program, either conventionally or via a neural net, so there will be errors in the system.
In the end, you'll probably have to wait until you return to your car to learn what happened, and you may not know even then -- as the clips the car records have no sound, you wouldn't hear an ICE vehicle's backfire, for instance. You could try contacting Tesla to see if those 6-second clips mentioned in the manual can be retrieved, though.