"Yea, thieves," he says readily. "We did but fight some thieves, Percy and I. And...we in our humors, being sorely provoked" he continues, with a sidelong look at Harry, something that's a little bit apology and a little bit mischief, "Did perchance hit harder than we knew, the both of us. And the thieves. --Marry, but who is thy friend Feuilly? A fierce swordsman, to keep practice with thee."

Hey, if Harry's going to call him Monsieur Monmouth, Hal is going to ask him about his friends. That's how people relate to each other, right? "I thank you, Doctor. 'Tis plain the future holds many wonders, but 'tis equally plain that the universities and physicians of Paris are wonders themselves."

It's clearly a set piece of courtesy, but not at all an insincere one.