Yes, at the prodding of the reviewer (from wikipedia):

> After the announcement, Nick Katz was appointed as one of the referees to review Wiles's manuscript. In the course of his review, he asked Wiles a series of clarifying questions that led Wiles to recognise that the proof contained a gap.

It seems likely Katz played a crucial role here.

Wiles is just a prominent example. In practice, other humans often play this "verification role" for mathematicians, whether via a formal review process or informal discussion.