When does media say 39% is not a majority ?

In the case of Canada, it is whenever the NDP or the Bloc or (heavens !) the Greens - and not the traditional two biggest/oldest parties - gets a majority of the legislative seats, based upon 39% or less of the popular vote.

Yet in fact, the last true majority at the Canadian national level was almost sixty years ago (!!!!), when Conservative John Diefenbaker got support from 54% of the 80% of the electors who turned out to vote.