Actually, this was supposed to be
Canada Post's first commemoration of a living subject (other than the monarch) #2212 (2005)

She died, however, on November 14, 2004, just seven months before her stamp was issued.
Previous issues (astronauts & hockey players (the latter whose names are not on the stamps themselves) were allegedly for celebration of the concept in general, not for any particular individuals (Yeah, right!)
On the other hand, according to the Canadian Postal Archives: #380 (1958)

"This was the first Canadian postage stamp purposely designed with a living model as the featured symbol of the theme the stamps express."
Presumably, some kid (other than Prince Charles) could brag to his friends, "My Mum's on a stamp!"