Just keep it for your 'rough use plate' and order another one (if it is a real crack). I'd be surprised that the piece had not just fallen right off by now, if it is a real crack. Perhaps it is some kind of a fusion or crystallization line in the granite?
On second thought, you could always contact them and send the pictures in. I doubt that neither you nor they would want to pay the freight on moving the dud around, and maybe you could get another one for just the cost of shipping or even for free.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)