Quant Dropped 8 points on the real test. Why?

Hi, I took the GMAT (2nd time) and my quant dropped 8 points.(46->38) ! I'm trying to figure out why because I consistently score around 45-46 on practice tests. (I've taken at least 15 practice tests from a variety of sources) Halfway thru the exam, I started noticing that the questions were really...