a question about memory

I was talking to a friend.  They were recalling a time when their uncle stopped.  My friend said that they could remember in detail the uncle pulling up in his car in front of the house.  Bright sunlight.  Getting out of the green, overstuffed chair and greeting said uncle at the door.

This uncle lived in the same town.  He often stopped by.  Why, my friend wondered, did he so vividly recall this one particular episode.  My friend does not recall that the visit was of any great import.  My friend says that he has recalled this uncle visit recollection more than 10 times during the 25 intervening years since it occurred.  Why?

I have some similar recollections that share the insignificant, one of many and oft recalled features of my friend's memory.

I have a theory.  Perhaps the memory is emblematic.  It might serve as a general memory taking the place of many particular memories.  That might also explain the repetitive nature.

I've forgotten lots of important events in my life and many others I remember that they happened but could not relive them and remember details the way my friend can remember a visit by his uncle one day.