It is frankly hard to say. I am thinking of my nephew, now 40 years old, married with two kids of his own, and successful and happy in his life. He was always rather isolated in relationship to peers. He never seemed very interested in these relationships and didn't establish many. He turned out fine and did not get any professional help.
Kids are different.
Your son may just be somewhat introverted by nature. If he is happy and doing well academically, then I wouldn't worry too much. If he seems to be continually hurt by peers and ostracized by them and is withdrawing from them because he feels rejected by them, then you may want to consult with someone professionally and see what they think. Hope this is helpful. It may be duplicated for distribution only with Karen Martin's permission.