Yale battery level dropped to 0 then increased to previous value

Strange experience today:

I was outside and checked my dashboard app: Battery level of my Yale is 0 !|
When I came back, the Yale was normally locked and worked as expected, no warnings.

I checked HE logs and the battery level of the Yale was 0.
Rebooted HE and voilà, the battery level is almost the same as before (was 68%, is now 63%)

I'll change the battery set (1 year) tomorrow, but any clue ?

Thank you