How often do you wonder if you locked the front door? Or turned down the heat? Or closed the garage door?
If I got a nickel for every time I went back to check if I had done something, I would be a rich woman. I am not sure if it is an "aging" symptom because I believe I have always done this. And my daughter does the same thing.
Did I unplug the curling iron? Did I remember my keys? Did I turn off the coffee pot?