TED Talk on how to improve ageing
I would bet the people in the "Blue Zones" they refer to have few regrets.

But yes, there does seem to be something in it when the OP asks I'm just curious as to whether this is a common phenomenon with age, or if it's just me.

Maybe it is part of the other phenomenon that comes with age, particularly retirement, where the important things in life may be sorted and the experience of age puts all sorts of memories, good & bad, higher up the priority for attention.

And little of it from 10 seconds ago when I went upstairs for, er, what was it?