You know, I’m not sure to what extent she was annoyed.
Before she asked him her question, in relating the story of her grandparents she had (thereby and explicitly) identified herself as being of Japanese ancestry, as opposed to, say, Chinese or Korean. So, in the first place he was (obviously) not just making an appearance-based assumption about her origins. Second, her “correction” was idiomatic but what he had said was not technically incorrect, either: the original phrase, Konnichi wa gokiken ikaga desu ka? simply means “How are you today?” — not an egregious or offensive mistake for him to have made. And third, when she corrected him, he responded with “I guess it’s after 10” — which, I concede, may not have been as politic as it was subtle.
So was she annoyed? Perhaps a little.
Here’s the exchange cued up properly: