So there is a MAP K-1 level, and I'm going to guess he's a smart cookie who scored high on this version the first time. The second time, they MAY have switched him to the grade 2-5 version, which contains harder questions. OR, he just encountered harder questions on the same K-1 version and got fewer right on that day. Either way, he obviously did very, very well.
FWIW, my DS had scores similar to your DS at that age and he is now a DYS who has skipped a grade in math. I am going to guess your DS could be at least gifted, if not HG+.
