This morning around 1000 when I got up to change the time for daylight saving on my FC-365 I also noticed the date wasn't correct, it was showing the 9th and not the 12th (I don't wear the watch but once in a blue moon). I was able to pull the crown and adjust the time with no problem as usual. I pushed back in the crown and gave it a few winds (although its kept on a winder so didn't really need it). Then when I tried to change the date with my toothpick (as I always do), it wouldn't budge. Nothing, no movement at all? Push push push and nothing. For sh*ts and giggles I tried changing the day on the other side with my toothpick and it worked just fine.
Anyone have any ideas on what could be wrong with the date function?