It is possible that Moses saw it. Although I don't think he ever made the claim for himself, St. Francis of Assisi was supposedly the first to experience this sign. An amusing story comes from our own day about a lady in Iowa City who had such wounds in her palms. When she returned the game, the wounds promptly disappeared. We might be impressed with the fact that Samuel heard the very voice of God.
Few people can make that claim.
In fact, we are told that God came and stood beside the boy to converse with him. I'm fascinated that his friend and mentor, Eli, had to call Samuel's attention to the Source of the call. The Epiphany Season always reminds us that several centuries after God walked up to the side of Samuel's bed, He literally walked the Galilean hills and shorelines seeking followers. Sunday's Gospel lesson tells the story of Jesus finding Philip. Jesus wasted no words.