Work: AM heat therapy, walk – 3 laps of our current “big” loop/PM long groom.
Report: walk – some concern, some yawns. He wasn’t completely over it but he was on a loose rope the entire time & he didn’t escalate, which for him is a biggie.
Ramblings for the day: When Rodney is concerned about life, e.g. at the top of the hill, i.e furthest point from the barn, he will chew on the end of his leadrope, much the way you or I would gnaw on a thumbnail.
We are making progress with the previous inexplicable behavior. He still runs to the barn when I get the mare for her walk but now, after a bit, he will come back out to graze. A reader suggested that he did this from a herd dynamic and a fear of being left alone. A legitimate theory for horse behavior. However, in this case a) he may be many yards away at the time and b) he shows no interest in staying with his supposed buddy.
Have your horse’s tics changed over time?
Virtual Brush Box 
Showing no interest in staying with his buddy — classic horse-show separation behaviour. It’s not that they’re particularly close, it’s just that they want to know SOMEONE familiar is about. Horses totally indifferent to each other bellowing like idiots when separated at a show … you’ve seen, I’ve seen it. No-one ever said they were bright. 😉
As for the tics … my gray mare flaps her lower lip when she’s out of her comfort zone. Which is often, as she’s pretty neurotic. The only difference in the behaviour over time is that she’s slightly less neurotic now than she was when I bought her off the track 12 years ago, so she does it slightly less often.