My understanding is that IQ scores at your son's age are not stable, and you are correct that you should wait to retest until he is older. I would not concern myself too much with testing for him now unless it will give you information you need or you have other concerns. Also, very young kids can get tired during testing, or if they don't feel comfortable with the tester, they may not answer and they get marked as not knowing (even if they know). All these things could contribute to your son having a lower score. But there are other people on this board who may be able to give you a more educated answer.
