I think Meanderer is right, we usually remember the things most important to us. I too sometimes have trouble following a movie plot, or remembering specific movie titles or actors, etc. There are things though that happened in my younger years, that are very clear in my memory, good or bad.
Since I had an aunt who died from Alzheimer's, I've been noticing more about memory issues as I age. But honestly, I forgot a lot of things when I was younger and working, and just blew it off to multi-tasking, being preoccupied or plain spacing out. Only as I neared my 60s did I start to think twice about any forgetfulness, regardless of how petty.
I agree with Ameriscot, if you find your keys and are unsure what to do with them, that's a big red flag. I take many supplements, including things like virgin coconut oil daily for brain health and memory. I personally prefer to try to prevent such demetia issues if I can.
Exercise is also good for the brain, and overall well-being. I always figured old people had trouble remembering things, that's expected as far as I'm concerned, it's forgetting who you are, where you are, or who your spouse is that deeply troubling. My heart goes out to all who suffer with AD, and their families.
When I'm at the gym I'll use different lockers, use different number codes, and sometimes take different routes to usual places I go to, like stores, etc. Getting out of a rut, and doing things differently than normal is always good to help you stay aware.