I don't think the score fluctuation is a big concern. It certainly will happen given the test format.
For example, in math, your problems get harder if you answer them correctly; and will get easier if your answer is wrong. The final score depends on the number of rights and wrongs at each level of difficulty. However, "hard", "easy" are quite subjective, especially for science.
Your DD has good scores. Do not read too much into a test score, especially the multiple choice ones. They are geared towards "one minute solution" problems, probably the reason that our Harvard/Yale graduated presidents do not understand complicated world problems.
