Well... it is theoretically possible but nobody knows how the GMAC algorithm works for sure (well, we sort of know the general aspects of it but we don't know some of the specific nitty gritty details).
I think you got hammered in that test but it is supposed to be adaptive so as long as you kept answering correctly, it was supposed to to give you hard questions. At the same time there are supposed to be experimental questions which vary in difficulty and also I feel that GMAC has a system (this is only a theory) that mixes in average questions during the test (or at least that is perhaps an impression if one is up/down right/wrong) which prevents you from burning through hard questions since it is a lot more expensive to create hard questions than easy ones. Meaning I think they adjust their system for the pool of questions available like they do on the GMAT Prep Tests 3-6 which have very small pools of questions. Anyway, I don't think you need to worry about it but you do need to expect that you will be getting hard questions if you are doing well.