My two girl, both in gifted programs, one in DYS, had scores drop in 15 of 58 sequential MAP tests, four times by over 7 points. And sequential -4, -5 changes once. But then +10, +7 on the next two. I wouldn't overly stress - but do discuss with the teacher. In our school, at least, it's not possible to be "kicked out" of the gifted program. Most important, I'd tell the little one not to worry about it. 8yo's don't need to be worrying about things like that.