
I would only add that it is natural to be protective of the baby, and it could be that you have never yet given him the opportunity to satisfy his curiosity about the baby.
When you are both there and you have the dog on lead, let him see the baby after a bath, so that he can smell the naked little person unencumbered by clothing etc.
My first dog a Belgian shepherd (quite highly strung) was fascinated by the baby to the p[oint of over excitement, and I thought she would sniff him up her nose!!!!
I very calmly allowed her to thoroughly investigate him (though she knew exactly what gently meant), after that she was not as interested in him, and would just lay her head on my knee while I breast fed.
I know it isn't the same but I have found a similar over interest in my other dogs (who haven't had the experience before) of a new litter. they keep wanting to sneak up to see what is going on, but once the pups are downstairs and they have had a chance to see they loose interest.