It's not that Galade's occasional references to this have gone unnoticed -- it's that Lanselos has no idea what to do with such a notion, and so he hasn't mentioned it. Of course, he in this situation, he has no choice but to respond.
He glances back at the mess hall, then takes Galade's arm and steers him a little ways away. Carefully, as neutrally as he can, he asks, "What do you mean, exactly?"