re: In an airport...
He thanked you because these guys like it when we take account of what they're doing, as you did. I've never offered to buy a veteran a drink, but I did manage once to sneak around some uniformed military people in a restaurant and pay their check anonymously. Whether they were combat veterans, I didn't know, or care.
I liked the idea of them looking around, and thinking anyone in the room could have done that.