That was always one of my favorite Columbo scenes because it seemed like something the real Columbo would do. I was exceptionally PO'd when Bravo cut that scene out of a rerun of that episode. To me that scene spoke volumes about Columbo the person.
I think you've made an excellent point! Which really brings up a related topic--are there any other scenes from other episodes that appear to be "accidental" but were left in because they seemed true to the plot or character?