All part of the fall out from the Arrow. In cancelling the Arrow, Dief agreed to acquiring the Voodoo and Bomarc, both of which were only of any use when armed with nuclear warheads (in the Voodoo's case on the Genie missiles). But then Dief refused to take the warheads. It became an issue in the 1963 election with Pearson campaigning on the side of take the warheads and winning.
As to not talking too much about the issue in later years, after Trudeau dropped the nuclear role in Europe it seems to me that pretty much all Canadians just took for granted that Canada was no longer in the nuclear game at all, despite the fact that until the CF-18s arrived to replace the Voodoos, we still needed those warheads at Comox and I assume Chatham and North Bay.