While he knows the odds of Hiei offering any warning, the laugh catches him off guard. He can't help the smirk that accompanies it, shrugging faintly at the suggestion that they'll figure it out. At least the invitation was there, should it become relevant in the future.

“Mm... True. I just thought you might like the option.”

Of course, he's also not thinking about the fact that his presence alone was enough to enable the fire apparition to get a restful sleep.