S9 recording glitch?

Hi. Last night I turned on my S9 at about 10:00 pm, and at 1:00 am, when I woke up and checked it, it said that I had used it for 1.5 hours. This morning I am still one and a half hours "short" on data compared to actual sleep time. No big deal, maybe, but I just wonder whether I should be concerned and whether anyone else has experienced this. We had no power outage, and as far as I can tell, the machine was on the whole time.

I am about a month into CPAP use, starting to experience benefits. Recently switched to Swift Fx mask (gotta change my profile).

Any thoughts would be appreciated. Big thanks to all who post here. I am learning a lot.

Just a thought...

Check to make sure that the time is set correctly... it may be PM instead of AM and differences can occur when you pass 12PM.

Nord