It's been a long time since I've lunged him, which may be part of the problem, and while he was listening and following my vocal commands for upward transitions, he was completely ignoring me on his downward transitions (trot-walk especially). I had to bring in the line until the circle was too small for him to trot any more to get him to stop. I don't think he's unsure about the commands, because I was able to get him to do it well once or twice. I think he was just ignoring me! How can I slow him down when he's just not listening?
The other little problem we had was at the canter. He pulled and leaned against the lunge, and did not want to bend correctly, especially on the left lead. On the right, we got a couple nice transitions where he carried himself properly and bent correctly, but other than that everything felt very frantic, like he was just running into the canter and then couldn't hold himself. I let the line out quite a bit because I thought maybe the circle was too small for him to balance on, but that didn't seem to help any.
I think he might be a little bit stiff to the left, which could cause him to not want to bend, but could it be more than that? Hopefully this was just partly because it's been so long since he's lunged, but I'm not sure.