A large part of your brain's job is discarding information it doesn't need. It's why you can listen to someone talking while not consciously hearing the other conversations, the noise of the jet going over, the car horns, the clinking silverware, and all the other massive sensory input going on.

It's astounding what you don't notice when your mind is on other things. I have two cars I drive alternately, a Honda Pilot and a Eurovan. They have absolutely no resemblance to each other in any way. They even smell different. You could put Helen Keller in the two cars and she would know where she was. But sometimes when I'm driving one of them, and thinking about picking up my wife, the grocery list, the squirrel I'm trying to avoid, that idiot in the other lane, the idiot on the radio, or any of the hundreds of things that occupy your mind as you drive, I will look over for the GPS screen in the Eurovan (doesn't have one), or reach for the shift in the wrong place, or (I do this all the time) try to unlock the Eurovan with the button on my Honda key.

It doesn't help that wherever Sherlock Holmes is on the scale of instinctive observational skills, I'm on the other end.

Same for old memories, I suppose.

It's possible that the glitches you are noticing are something that happens throughout our lives, but only become more obvious when we are older, and have a much larger file cabinet of memories than a young person does.

Life is a journey, but one where you can't really go back down the road and make a different turn. Remembering mistakes and wrong turns is a good thing--that's the "wisdom" part--but when you think about it, remember all of the scenery is pretty much all about the nostalgia.