Yeah, an American dollar will only get you 0.994390 Canadian dollars today. Such a big difference! 
I hope that means OUR money is Monopoly money too. I remember when it was closer to 2:1.
Not likely he randomly ran your plate. More likely he looked at last year’s date on your sticker.
Many years ago (pre internet commerce) I was washing my car one nice spring day when I realized that my registration expired the previous Oct. Called DMV to send out the proper form, called them again a few weeks later when it still wasn’t received. Only then did we realize that they were sending it to the old zip code, which USPS had changed during the past year. Finally got the form, & mailed it back with a check. A few days later, I went to local PD who confirmed it was now valid in the system. Of course, the very next day I get pulled over for expired registration. “Oh no ocifer, it’s valid; why don’t you walk back to your car & check it in the system”. He comes back & hands me my paperwork back, with a 'have a nice day." I could’ve pressed my clothes with the steam coming from his ears.
This coupled with the fact that there was a wave of license plate vandalism by people tin snipping the corner of the plate to get your valid sticker & tape/glue it on to theirs so their plate *looked *valid means I haven’t put a sticker on my car in years…& never had a problem for it. YMMV.
Interestingly, in my registration pullover mentioned above, it expired something like September 5 2011. My sticker said 09/11, which really meant it ended anywhere from September 1st to 30th. I don’t know how he decided it was pull over-able, as he didn’t have enough time to run my plates I imagine. He was too polite for an officer, I didn’t ask.
I was once pulled over for the license plate sticker being out of date. I was very young and had assumed my Dad had taken care of renewing it. But the weird thing was the circumstances – it was a moonless night, in an absolutely driving rain, and I was traveling at highway speed when I passed the cop at right angles. He cannot have had more than a split-second to see my small license plate sticker, a good distance away, through his rain-drenched windshield.
Standing at my window in the rain, he apologized for the necessity of pulling me over. I just shook my head and said, “Don’t apologize, you’ve earned this one.”
Many moons ago I was pulled over and given a ticket for an expired licence plate sticker. I’m not sure how it works now, but at the time if you went and got the registration, then appeared in court to show that you had done so, the ticket was dismissed.
While in court waiting my turn, I heard all manner of ridiculous stories from other defendants attempting to explain why they had let their registrations expire. When my name was called and the Judge asked me “Why were you driving on expired plates?” I said, “I have no excuse, your honor, I procrastinated.” He laughed heartily and said, “You’re the first honest person I’ve had all day!”
Wow, in my court you are looking at a minimum of $300.00.