COSTCO sells Picasso Doodle

(Thanks AJ). COSTCO (yes, yes... COSTCO) has just sold a Picasso doodle done on the back of a bookcover for $40K. Read the story here.

They currently have a Chagall litho (several Chagalls actually) and also a Modigliani litho and a Leger litho for sale.

I am curious as to how these works, and works like this one get into the COSTCO system?