Moses didn't look

We make much of when Moses asked to see the face of God and He told him no. But look at this:

Exodus 3:6 "Moreover he said, I [am] the God of thy father, the God of Abraham, the God of Isaac, and the God of Jacob. And Moses hid his face; for he was afraid to look upon God."

In the first case Moses would not look at God. It's therefore so much bigger a moment when he is able to ask God to show him His glory. Over the course of his experiences Moses was moved to a place where he could trust God enough not to destroy him for his sinfulness. He came to terms with the goodness and mercy of God. First he did not, then much later after seeing who God was, he asked. Like Peter who begged for Jesus to go away, and then turns and confesses He is the Christ, the son of the living God.