If Setsuna were better socially trained, he might've pointed out that he lived in Japan for a little while. But he still has only the social grace of a turnip, so rather than mention that, he simply asks "Is that what you asked us here to discuss?"

Not that he'd be offended if it were. He'd find it a little strange, though. He's fairly certain this isn't some kind of 'date' (Wasn't she involved with someone anyway?), but he figured Sakura would know better than to invite him over for tea and idle conversation alone.