I bet he is doing that male bucking that some males do when females are nearby (I'm talking about Ball Pythons, y'all..)
I had my male for 6 years before I decided to breed him to the females. He only occasionally did that "get off twitch". Once he got to be around the girls, though, whew !!!
Every time I tried to lift him out of the tub his whole body would arch and he tried to literally fling my hand off of him. Once picked up he would buck hard enough to almost jump out of my hand !!! He was soooooooooooo TOUCHY during that time. After three or four bucks he was usually done after picking him up.
He stopped doing that after breeding season. Went back to normal. I've had a few snakes do that "back off" fling with their body. Even seen them bounce small rodents off of them. But the only time I've seen this so extreme was in my male. During breeding season.
Is one of the snakes you are watching a female ? Could you have handled a female and then, while her scent was on you, handled the male?
They certainly can smell a female, one nearby, and on you as well. Maybe he is in breeding mode and moody and twitchy.
Of course you need to rule out any overheating, toxins, etc.