That's fine, but it never even occurred to me that "no problem" would be commonly considered impolite. I mean, if it was an undertaker who said "no problem" after he had mistakenly put the wrong body in a casket....that's one thing. But if I ask for wheat bread instead of marble rye and the waiter says "no problem," then I'm not going to bat an eye, let alone consider him/her "less intelligent."