You can always manually reset the battery log time with the button in the upper right corner on the battery display (recycle).
BTW, I am having some weird battery issues myself. Twice now the battery has drained for short periods for no apparent reason. It is doing it in sleep mode. Besides some battery issue itself, my guess was that it is trying to connect to WiFI while sleeping and having trouble, some app is still running, or my case I just got is doing something funny with the open/close. Still troubleshoot (not using the case first).