CGC will regrade the book during a page quality review if they feel that the book does not represent the assigned grade. I had a Detective Comics #10 CGC 4.0 Cream pages drop down to a CGC 3.0 c/ow pages on a page quality review.
Yikes Sorry to hear that!!! From what I understand, if there is damage to the CGC holder or if the book was damaged inside the holder, than the book will be regraded. But, if the book still remains the same in its holder and there is no damages to the case, then they will just regrade the PQ by writing it on the submission form.