Perhaps you can reassure your husband that the way your son behaves is not a personal attack. Some people are more introverted while other extroverted (and it sounds that your husband is an extrovert) People also have different styles/ways of communicating information to each other. Try to have your husband focus on the positive, perhaps on experiential things such as sports, fishing (whatever the two of them can share as as common interest)
You are correct. Relationships and harmony develop over time. Perhaps your son is being cautious fearing disappointment. That may be the reason for appearing more reserved as well as his personality style.