Sentry mode doing its own thing?

[Wol747]

I parked in a multistory carpark by a destination charger (which was as usual u/s) and when I returned there were 57 sentry clips.
In none of them could I see any movement - not a pedestrian or car passing - but they were each exactly one minute apart for the duration of the stay.
Could this be a new feature of an update?