My cousins son has Autism and he spins everything abnormally. If he has a truck to play with, he flips it upside down and spins the wheels. If we go into a store with ceiling fans he alternates between watching the wheels on the cart spin and watching the ceiling fans spin.
Usually all of the spinning activity was done by using toys in an abnormal way. He also had a number of other delays which lead to an early diagnosis.
Since your son plays with his toys normally and seems to be developing normally I would think that he is a normal little boy :). Try not to worry. If your concerns continue though you could talk to his pediatrician about it.
As for your husband's spinning... if he is spinning the ring around on his finger that is a normal activity, if he is taking it off and spinning it and everything else he can find on a table, then perhaps your son is just picking up that activity from watching your husband.
I have to be on the watch for Autism in my youngest since infants who were born extremely premature often are Autistic. I have been communicating with my cousin (whose son is Autistic) and going through my college psychology books to re-familiarize myself with it. I do know that the incidence of diagnosed Autism has increased dramatically in recent years and that there are many studies being done as to why. Many suspect that a group of children labeled as Autistic are misdiagnosed, and research is being done to learn more about Autism. Since this research makes the news often, parents are more aware of the problems associated with Autism and then tend to watch their children more closely. While it is good to get all the information possible and get an early diagnosis if the child truly has Autism, it is tragic when children are misdiagnosed, or when parents spend time worrying when they do not need to. Try not to over analyze your little one. Just relax, enjoy him and keep a mild eye on his behavior :).