I'll admit I've not spent much time in Canada. Most of the time I did spend was driving along the top of lake Ontario and then back into the US via Niagara. Most of the flags I saw there were British!
Fascinating. I'm Canadian too and have made similar observations, yet was surprised to read what you wrote. Our self-image is so strongly one of not being nationalistic that we're for the most part unconscious of this behaviour. Most Canadians would react to your comparison to Texas as an obvious joke or a weird paradox.
I suspect this Canadian flag-waving has more to do with our insecurities than it does with our comparative level of patriotism - we're not all that different from Americans, so we go out of our way to emphasize what differences we do have.