A friend of mine told me something interesting a while back.
When they make a new product, they send it from the factory/distributor to the stores/chains a while before the sales schedule.
Sometimes a store screw up date, or knowingly sell it earlier that it should.
Imagine a BD in 1'000'000 copies, put on a bunch of trucks, shipped to some warehouses for storage.
Theres bound to be alot of people that know about it. It only takes one to make a rip.