That the score is slightly lower is a non-issue. The standard error of measurement (SEM) on the MAP is about +/- 3 points, so you're talking about an insignificant change in scores. Stagnation is another question. That depends on what his original score was. If he was already essentially at the top of the norms, there wouldn't be much space for him to grow on this test. Also, going from grade 2 to 3, he may have switched over from the MPG (grade k-2) to the grade 2-5 version of the MAP, in which case the scores are not as comparable (in the upper extreme of the MPG).
IOW, it's difficult to interpret the significance or the meaning of these results without a bit more context.
