Does anyone have the problem of the rectangle stone not sitting flat on the rack? I have a customer and hers is a good inch off the bottom, thought it was the wrong size rack so she ordered another and it also doesn't sit flat. I finally ordered one and mine doesn't sit flat either, however, it is only off maybe 1/4 inch or so...HELP!!! The lady is really frustrated and I don't want to turn her off the PC!!!!