I did drive that day, and I suppose it's possible that I made some mistake at a toll booth or got caught by a speed camera, although I generally set cruise control on highways to avoid that. It has been about 20 years since I've had any sort of infraction, so it wasn't anything intentional, for sure.

The pdf attached has my full name and my correct address, and says if I have a dispute to take it up with the issuing authority. I have no idea what the fine will be when it arrives. It's kind of frustrating, but it doesn't appear to be fake, and is not asking me for any money or anything, as they will apparently just ding my CC for the amount.