According to http://www.vancouverhistory.ca/chronology1961.htm:
The switch by the world’s airlines to jets would mean a major overhaul of Vancouver International Airport. A figure of $100 million was cited. The city voted to sell the city's share of the airport to the federal government for $2.5 million.The Canadian government expansion of the airport for the jet age began in 1962. It is 232 km from Vancouver to Mercer Island according to Google Maps.
Entirely possible. But just because the airport update was done until after 1961, doesn't mean jets could not operate there. Generally those updates were mostly for the terminal buildings. Adding "jet ways" and so forth. But even the early jets could use most existing runways designed for the larger proppeller driven aircraft. The airports just couldnt' handle the large volumne of traffice that the "jet age" was to bring. JFK flew into Dallas Love Field in a 707, and that was and is a pretty old facility. The terminal was upgraded, but I doubt the runways were. Still it was used as the main airport for Dallas until '74 or so, and still serves Southwest Flying fairly large late model 737s and some MD-90s from other carriers. I flew through there in '74, I think in 727 IIRC, which took a lot of runway compared to a late model 737.