My 4 yearl old nephew have a small penis. too small for his age, should we concern?

Dont do anything: Especially examine him, it could be construed as sexual abuse.

May be just see...: Baby chubbiness may make the penis looking relatively small although occasionally a buried penis does exist but very rarely. For a 4-yr boy, i would recommend just wait and see as long as he is growing and testes are present. Of course, if in doubt, see his pediatrician timely for detailing.Best wish...