I don't think it is as much of a mystery as a shell game. They have lots of US $$$ and the ability to buy mine direct, all they have to do is offer just a little more than the going rate and Bob's your uncle! Lol...
This would create inventory on there balance sheet without having know stores show a depletion of inventory.
Now I could be way off and you can call me out on it if you like but it's a sound theory IMO