@Merry Andrew,
Now that you've pointed it out, Andy, I have noticed young folks adopting that tone, making it rather obvious they're on uncertain ground. Probably comes from being told not to say "you know" all the time.
However, in the case of the Canadians, their "up-speak", or whatever, to me doesn't hint of any lack of confidence in what they are saying, but makes it seem as though they're asking rhetorically, "are we on the same page?" Like a Plum Wodehouse character appending "what" to a statement, you with me?