Chief was used to surprises, he'd been through it all. But on a more loose connection ship, one with less contact and such Chief had a brief moment of confusion.

He'd been waiting around, trying to focus his mind on something. While waiting he saw another Spartan, Chief knew there were other Spartans on the ship he just didn't expect another Spartan II, much less one he didn't know. Chief wasn't one for confusion but in that second Chief definitely felt something similar to it.