Again it’s happened twice. Someone has mentioned “Shimotsuki” but Zoro is conveniently not hearing it.
The first time, Brook was gonna say Yasu’s full name and Zoro cut him off before he could say it and later all the people around Yasu’s execution say his full name but Zoro isn’t around. When Zoro arrives, Yasu’s dead and no one is saying “Shimostsuki” anymore.
And now, when Kawamatsu is telling Hiyori about the Shimotsuki family, Zoro is once again, conveniently not around and by the time they meet Zoro, Kawamatsu is done telling the story.
Who’s betting the moment Zoro actually hears the name “Shimotsuki” anywhere in Wano, we get a flashback to his childhood?
I think Zoro will hear that name the first time when someone tells him about Ryuma because his name is also Shimotsuki Ryuma.