I do know that Testors was bought several years ago by a major company, and they also own I think it is the Rustoleum and PollyS line of paints, and some others. I have seen where they have dropped some of the colors from some of the lines of certain paints, but then brought it out under a different line of paint. Testors use to have the Boyd line of paints, and I have seen some of those colors now being offered with a different name (ie dropping the Boyd name) under another Testors line. I have also seen where they have discontinued some of the Testors Metallizer colors that I wish they would bring back.
It is possible that a hobby shop may have tried to order some paint from a distributor that didn't have it available, and possible misunderstood why it wasn't available for purchase. I have looked on the Testors website, and the One Coat Lacquer line of paints is still shown there, though the wesite seems to be harder to find things lately, and there is nothing saying it is not available or being discontinued.