Fluctuations happen! For me it was influenced by how rested I was, what else I had going on, and the topics on each practice exam. I wouldn't worry about it. Here is what my exams looked like last summer.
Test 1 (early June, before doing much review) AAMC sample: C/P 70%, CARS 68%, B/B 74%, P/S 80%
FL1 (8/1): TBR1 C/P 130, EK1 CARS 123 (ouch), Altius1 B/B 127, EK1 P/S 128 = 508 total
FL2 (8/7): TBR2 C/P 129, EK2 CARS 122 (starting to stress), TBR1 B/B 129, Altius1 P/S 129 = 509 total
FL3 (8/10): Altius1 C/P 131, Altius1 CARS 125, EK1 B/B 127, TBR1 P/S 128 = 511 total
FL4 (8/15): EK1 C/P 129, EK3 CARS 124, Altius2 B/B 128, EK2 P/S 129 = 510 total
FL5 (8/20): TBR3 C/P 131, Altius2 CARS 126, TBR2 B/B 129, Altius2 P/S 128 = 514 total
FL6 (8/23): AAMC 1 C/P 131, CARS 126, B/B 131, P/S 130 = 518 total
FL7 (8/30): AAMC 2 C/P 131, CARS 124, B/B 131, P/S 129 = 515 total
FL8 (9/5): EK3 C/P 127, Altius3 CARS 124, TBR3 B/B 129, Altius3 P/S 128 = 508 total
FL9 (9/13): AAMC 3 C/P 131, CARS 123, B/B 130, P/S 128 = 512 total
MCAT (9/18): C/P 132, CARS 122, B/B 132, P/S 130 = 516 total