He was doing it again yesterday!
I now don't think it's shedding behavior anymore. This does coincide with an increase in humidity in the air (it's very high, although I haven't measured it, I'd guess 80%) and a decrease in ambient temperature. Again, the snake was all up in the pothos and manzanita branches.
Anyway, as per last time, I gave him a nudge with some tongs and he jumped back into the water. But he seriously looked dried up, almost like he got stuck up there. Except that he had no problem getting down.
I tried getting a video but his return to the water was too fast. But, when he ran off he startled one of my frogs, which gave me a great video opportunity.
So if nobody on here is keeping them these days, does anybody know somebody who does? I know they have them at the Central Park Zoo in NYC, but emailing their info address does me no good.