If it's any comfort to you, about 4-5 years ago I totally blanked out on how to turn on the windshield wiper fluid. It totally freaked me out. I had to pull over and look it up in the damn manual. But nothing like that has happened since then. So know that it can happen...but that it doesn't necessarily imply anything bigger.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks