I wouldn't get too worried that something is wrong, though, if you have no other reason for concern (do you?) My father can be like this, unfortunately, and I suspect he always has been. There is nothing else wrong with him, but he is extremely smart (probably PG) and by nature impatient.

However, I think you could work on this behavior with your son. I have a child like this and we're always trying to work on it. Does he correct people a lot? That really aggravates many people, even if he's right. We are always trying to make DD think about whether she NEEDS to correct people (ie, will someone be physically or emotionally hurt if a correction is not made?)