Early signs of dementia??

Arghh!! I missed my workout session at the gym today because I had the wrong date/time in my head. The worst part is that I only discovered this AFTER I got to the gym, was about to scan my card and go in when I realized that I didn't see the session on the schedule, so I walk over the reception and say " isn't there supposed to be something starting soon?" she says, " uhm no, they started about 30 min ago". As she's saying these words to me, the realization slowly dawns on me that I've mixed up the days.... At least this means I get to go home and have lunch instead :)