I don't see a problem here, just say that these cats were raised a certain way, and are the best behaved of the bunch. In fact, acting out after this would only be more suspicious.
Best thing to do is just say some customer service pablum like "We're glad they meet with your satisfaction, miss" and then don't engage further with it. Maybe double down with a cheeky "Please let all your friends know that our cats are the best."