The glass pieces were actually warped which causes them to not sit flush in the metal frame.  That causes the glass the move up and down every time you put something on the table.  The little rubber bumpers they send with it are too small the compensate for the amount of warpage in the glass. Wayfair of course is sending a replacement, but if this is a quality issue then I expect the replacement table to have the same warped glass problem.  We’ll see.