While the elf is talking to the dog, Alistair is picking hay out of his hair and idly checking for weapons, out of habit rather than suspicion. Even if they weren't in a heavily-guarded fortress that none of the people who might want to kill Alistair (today) should know how to find yet, the dog likes him. That's a good sign.

But then there's his name. He checks again, less idly, but still not very concerned. His sword is propped against the wall. The horse master is within shouting distance. The elf looks--well. Particularly harmless, around the face, whether he's armed or not.

Still: "Why?" Alistair asks, a little drawn out and teasing--whhyyy?--with his eyebrow arched. Maybe--probably--that's an answer in itself, but he isn't really trying to be sneaky. He's no good at sneaky.