"I wonder as well how widespread this is across Canada. I suspect that many are like myself in that I have never encountered a woman in this article of clothing. "

I have, and it is becoming more common, in Montreal anyway, as it has been for awhile in Europe and the UK, with mass immigration and the increasing influence of islamists, particularly online. 

We are not yet at the level of those, but you just have to look at the "poster girls" we are being presented by the media, all young women who have adopted the niqab recently, willingly, although they were not raised that way, their parents don't approve, etc.

It is an international ideological movement being presented to us as individual "choices".

http://montrealgazette.com/opinion/columnists/khan-the-niqab-takes-us-back-to-where-muslim-women-should-not-be-going/wcm/9029d115-0ce4-46d8-b436-5386be3322dd