This puts me in mind of the requirement changes that wire nuts went through back in '89. Wire nuts used to be Al/Cu rated until UL® added new testing requirements for the "Al" portion of the listing. Manufacturers quietly removed the "Al" from their wire nuts.
I had a conversation, then, with a UL® representative who stated that the use of the old product was still permitted until the old product was gone. This representative stated that the improvement of the product, practically speaking, took about ten years until all the stock shelves were cleared of the old product.
