The first thing that came to mind as I read your story, is that would have been a perfect opportunity to start a positive conversation with those around you. A chance to explain that you not only mean no harm to them, but would also be an asset if bad people showed up. A chance to explain that it is not only a RIGHT for an American to carry a weapon, but as some of us feel, a responsibility of citizenship. A rifle behind every blade of grass kinda thing. A chance to bring more of the sheep around to our way of thinking.
We carry 'cause we wish to be prepared, guns, phones, knives, flashlights, etc. It is also helpful to be prepared mentally, aware that when we open carry there will be some around us that aren't accustomed to seeing a person with a gun and no badge. Facial expressions expose someone's perception, and can be used to help determine if/what/how needs to be said.
Just as having the gun is a responsibility, so is being a good steward of the right.
Good for you keeping the scene neutral at least, for negativity could have arose.
BTW, I been in that Popeyes hundreds of times. I understood your senario.