Just thought of something. I bet your son was loving the story too and that is all that matters. You be you and enjoy life, your son will remember how wonderful your stories are.
Every year I would go trick-or-treating with my nephew. He would always let me know what he was going to dress-up as and I would match him. One year we were Peter Pan and Tiger Lily, the next Yoda and Darth Maul, the next Harry Potter and Hermione, one year batman. My brother was always "too cool" to dress-up with us, which to me and my nephew meant he was the uncool one. My brother followed us all through the neighborhood with my nephews red wagon filled with beer and ice sharing with all the other "cool" suburban alcoholic Dads making fun of us. You know what? My nephew only remembers how cool we were and how much fun we had. He doesn't remember my brother walking with us.
So you go on and tell those stories as loud and animated as you want! Let Mr. Sourpuss
be embarrassed. Next time you and your son should go wearing capes.