After the initial shock of sunlight and fresh (well, fresh enough) air and the fact that they would be walking for a week, Aziraphale had had the good sense to look around. Catching sight of Liam was no difficult task - they weren't, after all, a very large group - but Aziraphale hesitated to approach him. He kept asking himself why, and came up with several answers.

Because they might have done something worse to Liam than they had to him.

Because it had been his fault in the first place.

Because Liam might not remember any of it at all.

In the end, though, he caught Liam during a rest and managed a "Hello" before realizing he wasn't sure whether to say Sorry or What happened?