Sometimes things don't go as planed.  During the product build process, if a piece of wood which was dedicated to that build is cut too short or a piece of it chips out, the build continues but the either the product dimensions change or the flaw is simply included in the build.  In good conscience, I can't sell this piece at full price since it is flawed in some way.  

My mistake is your good fortune!  If you can live with a little ding or a fixture that is a slightly smaller than intended, you'll receive a nice discount.