The fact that Jack was honestly worried about York was an amusing thing to Ianto. If York hadn't hit on Ianto, it wouldn't even be an issue for Jack. Still, Ianto was willing to let it go, at least for now. They would need eventually to talk (yell) about it.
At the moment, he was far too comfortable to even think about it. "Things will come out when they need to come out," he protested. Or when Ianto felt like kicking Jack in the arse. One or the other. The little kisses brought small, real smiles to his face, though Ianto did roll his eyes. "Of course they're allowed. Don't be more daft than you already are."
All in all, Ianto felt, that the whole date wasn't all that bad. They had a lovely dinner, they didn't get run over by Weevils or aliens, and they actually had a productive talk. He was, frankly, amazed. "Thank you for the lovely evening, Jack," he murmured, laughter lurking at the edges of his voice.