Weller 12 has been generally unavailable in No. KY for most of the past year. Because of a shortage of aged stock, production was temporarily halted. A limited release was done a couple of months ago (primarily in KY and nearby states) but that quickly disappeared from local shelves.
A BT rep told me recently that the next production run will be around Derby time and in greater quantity than the last one. He also said that it will likely be a year or more before production gets fully in synch with growing demand.
Having said all that, there are obviously still quantities in the distribution pipeline elsewhere.