Ever experience sudden onset profound sadness for no apparent reason when not depressed?

I was having a good day when suddenly I was overcome with profound sadness and I could not pin down any associated thoughts or events. I take anti-depressants daily to cope with my chronic pain and have not felt depressed in many years.

I withdrew from contact with others for a few hours and it passed. Even as a trained psychologist, I found this odd.

How many of your (who are not depressed) experience such unexplained feelings of sadness and how do you cope with it?