It happened in a Walmart a few years ago, and nobody said or did anything for about forty-five minutes. When I was in the self-checkout lane, another shopper thanked me for my concealed carry. I checked, and discovered that my outside shirt was caught over the grip on my sidearm. I apologized for my screw-up and covered my exposed firearm. Nobody lost their minds. Sometimes, there are advantages to being around retirement age, and carrying a .38 caliber revolver.
A few years earlier, I was carrying a 1911A1 in a hardware store, and one of the store employees saw it. He went to the store owner to complain. When I was at the checkout counter, the owner asked to see what I was carrying. He had some questions about carrying a .45 caliber handgun before he went in to his office to bring out his AR, lever action 30–30, and .357 revolver. We talked about guns for twenty minutes or so, and the employee walked out of the store. I should have gone back later to see if he quit, and ask if his job was available.
Other people have probably seen my concealed handgun, and said nothing.
Here I am recreating my Walmart faux pas.