The first part is us going to the right, then we turned and went the other way.
I was like, "wtf horse? What is your problem! DO IT!" Yeah. Then he did it a couple more times when I'd ask him to canter that way.
Then I thought, "maybe he's not just being a jerk. Being jerkish is really unlike him, anyway."
So I checked him over and his left hock definitely has some puffiness going on. Not sure what's caused it as he doesn't appear to have been kicked and it wasn't warm or anything like that but anyway, calling the vet tomorrow.
Ugh. Keep your fingers crossed its something minor, please.
Here's a happy picture, at least?