Manners in Restaurants

I have noticed that the response given to a patron from the waiters or waitress lately... is "No Problem" , rather than saying , "Thank you, enjoy your meal." When the public is thanking for good service etc. , the most polite response, is not the no problem one. Of course, it is not a problem to be doing your job! The patron is saying thanks for the speedy service, and a respectful answer should be, " You are most welcome, if there is anything else you would like this evening? If not, then just say, "Enjoy your meal."