Practice Test Fluke?

<p>I normally score 750-800 on CR practice tests (QAS's) but on one test I thought I did really well on it but ended up getting like a 620...? I am worried now because I am thinking I could walk into the test day and think I did really well but ended up screwing it up. I got a perfect score on a CR test right before this 620 fiasco. What's going on????</p>