MGMAT CAT #5...what happened??

Here's what my breakdown looked like for MGMAT #2:

780 Q51/V45

9 wrong in quant
14 wrong in verbal

Almost every single question in each section was 700-800 level.

Now today I took MGMAT #5:

760 Q49/V45

5 wrong in quant
2 wrong in verbal

Almost every single question in each section was 600-700 level.

Here's what my quant difficulties looked like:

1. 300-500
2. 600-700
3 through 8: 700-800 (I got #6 wrong, but 7-8 were still 700-800)

then I didn't get another question wrong until #24, but I only got ONE more 700-800 question in the whole test! (#13). Everything else was 600-700 with #34 being 500-600 (without getting any of the previous 4 wrong before that)

I can't figure it out. The first four MGMAT tests were all very similar. I got almost exclusively 700-800 level problems, and when I got one or two wrong I would drop to 600-700 difficulty level but then after getting those right would jump right back to 700-800. Now I got a total of 7 problems wrong on the entire test and only got 18 700-800 problems in the entire test! PLUS, the quant section only had 36 questions! They didn't even give me a full 37!

I'm kind of at a loss here guys, this test seems to have been a waste of time. Any theories on what happened here?