Given that Sion had a Goodra that refuses to respond to anything other than "Boo", well, he knows how it can be with naming. Then again, even if he did think it odd, he certainly was too composed to let on to that fact.

"Oh? You must be quite good, then," he said. Dusk, meanwhile, nodded in response to the question. "Of course."

Or at least, that's what Ceilidh would hear; to Sion it was merely the usual poke-speak, though he knew Dusk well enough by now to know she answered in the affirmative even without seeing the nod.

... Neither of them, however, had the faintest clue of Gaelic.