Be very, very wary of your own personal observation bias. You obviously love your frogs (which is awesome) and you hope that there's more to their behavior than just basic instincts. This has a tendency to skew any observation you make and rationalize it in a way that fits your hope and cast off anything that doesn't support your belief. Like the possibility that it's a fear (or reproductive) response that puts your frog on alert. Or maybe the horror shows generally happen later in the evening, perhaps after an evening misting or after AC turns off. Higher humidity generally leads to a more open and thus less moisture preserving posture.

As for the frog settling down on you- I've handled many, many wild gray tree frogs (generally to move out of danger like the incoming lawnmower or off the top of the door that's about to be shut) that could have formed no attachment whatsoever to me. It is pretty standard that once I pick them up they cling to me somewhere and won't let me put them down someplace safe. I doubt this is because they like me and I've always took it to mean they are choosing to prefer being stuck to me to the possible alternate of being eaten. If you're a frog, it's a good day if you don't get eaten. So if you're not currently being eaten, you're currently doing alright so let's not let anything change if you can. Whatever it is, it's definitely NOT because they 'like' me, I was the strange giant dude who just about mowed them down after all.

Everything I've seen supports the three motivators Martin has mentioned and never to any kind of added emotion. I'm also sorry this is the case, but I find they interplay of these natural instincts so fascinating that it's never taken away any of my enjoyment of watching frogs. I'm always open to evidence to the contrary but I hold a very healthy skepticism of anecdotal reports.