He gives her a faintly curious look. "You don't know." But of course that's not really a surprise; Claudius likes to say that he prefers younger men and older women. Galahad isn't good at telling how old people are, but he's fairly sure Susan is more his age than Claudius'. Still, sex is a language for Claudius, and it sometimes takes Galahad by surprise that he hasn't tried to speak it with everyone.