I have not seen one either. That was a main factor in me jumping on it.
Nick Mutton informed me over on Morelia Pythons that it was not a Cooks. He explained that the differences were like I said so small, that people call them Cooks if the Amazon is in a certain Phase.
Not that I am THAT pissed about this whole thing, its still a cool butt Amazon. But It would have been nice to truly have something with the "rarity" that the Cooks hold