Considering the history of NAND flash amounts to Toshiba applying to Japan's patent office and getting laughed out of the room, then Sandisk saw it and applied

Considering the history of NAND flash amounts to Toshiba applying to Japan's patent office and getting laughed out of the room, then Sandisk saw it and applied for and received a patent for NAND flash from the US Patent Office, it's probably still the case.