I don't think so. Waitperson wouldn't chase them out for an extraneous tip. But if the tip was included in the bill, that was what the customer owed. Period. jmoSomething just occurred to me - being as it was the waitress who followed them out- could the issue have been that they didn’t leave a tip? Maybe that’s why they’re being so tight lipped about it? It’s not a good look pr wise.