That makes John laugh - not only is it cute, it's hard not to appreciate someone with a decent sense of humor as far as self-deprecation goes. Q is funny - slightly ornery but entirely too posh a Brit to ever sound anything more than mildly upset. John's used to that sort of folk, but it doesn't make it any less charming.
"No, no. You should keep saying it. Why would your friend want you to stop? It's bloody adorable." Oh, there was his wolfish grin again. Hello.