A little pry bar work solved it, the latch wasn't fully engaging with the striker so I angled the striker out a little bit and it probably gave it the extra 1/16th of an inch it needed to fully engage. It deployed twice yesterday while I was driving. If the pry bar hadn't fixed it, I found another pair someone was selling for $50 Canadian. They were for an '09-'14, but only the frame brackets appear to be different.

 

My side steps were on the truck when I bought it new. They work fine in the summer, but come winter the guck gets on them and they really like to stick and not deploy. Come spring, with a good pressure wash, they work again.

 

I expect it'll be the same situation here in Eastern Ontario and I really got them because I couldn't pass them up at that price. And if the previous owner got rid of them because of the latching issue, I'm glad I figured out how to fix it and his loss is my gain.