I was wondering if the lens was dirty, so I wiped it with my shirt (without breathing on the lens) and then decided to take another shot with the flash to see if I still got the weird "orbs" with the flash. Sure enough, I did. Almost like a snowfall of them. But the sky was clear and there was no falling or drifting snow visible, so what the hell is it?
My best guess is that it's tiny particulates from the bus exhaust. I walked over to the parking lot of the Kanata Centrum shopping plaza and took another flash picture to see if the same thing would happen there, but I just got a clear photo, so the bus exhaust theory would seem to hold some water.
Incldentally, I don't think it's water droplets from my breath. I later took a photo of my breath for comparison purposes, and it just looks like a cloud, not a lot of small reflective points.