I'm not a chef, but I saw a hidden camera with a disgusting report on one of the news magazines of what some chefs do to returned food. I could hardly believe my eyes, but there it was. I'm sure I'm not the only one here who saw it.
That was lovely that you were given a dessert for the compliment!! Very classy of the chef, and smart too. I'm sure you've told local people about the nice experience at his place.
If a chef is passionate about what they do then they will handle any comments in a professional manner. I've worked in a few restaurants in my life but have never witnessed this behaviour from chefs, though I know it does go on.