Yes, some scale folding is normal. Ever look at the inside of your elbow? See any creases? It's normal & much the same thing where we (or they) bend.
It's normal in winter for humidity in our homes (& theirs) to be lower, largely due to our home heating & also that winter air outdoors is cold, & cold air holds less humidity to start with. You might try to bump up his humidity in winter (especially if you see any shedding issues) but I'm just saying not to get extreme about it. Wild boas are well adapted to some variations- they certainly don't have perfect conditions for much of the time. Some even think that having little or no variation may make snakes less resistant, health-wise- & that having "perfect conditions for 24/7" makes them more prone to RI or other infections. I can see both sides of this. Stress & other variants (genetics etc.) probably also play a part.
When I had a BCI for many years (who, btw, was always healthy, shed & ate well, & never bit me), she seemed to love being out. I say that in part because she was a real "rodeo" to get her back into her home.

During that time, sometimes she was just nearby so I could keep an eye on her, but she also liked to snuggle around my waist while I watched movies- or in nice weather, I took walks outside, carrying her. She seemed quite comfortable with all of it.
Much depends on your own empathy & calm, reassuring handling skills- if your boa seems calm & comfortable, is healthy & eats well, I see nothing wrong with having her out (handled or not) for a couple hours. That's what I did too, though not daily. Note- in winter- when my house was on the chilly side (my home t-stat is set to 69-70*)- I provided a heating pad + my own body heat. It's still important that your snake isn't allowed to get too cold when out. When mine snuggled around me, I put a blanket around both of us to keep my heat in. If I thought she needed more, I added a heating pad. She was clearly very comfortable. And it sounds to me like yours 'enjoys' being out & handled too.
One caution: Mine would sit perfectly coiled on my bed while I went back & forth to another room, folding laundry, etc. But one day, after pretending to be a rock for a long time, when I was out of the room for not more than 5 minutes one time, she took off into my open dresser drawer to hide out. Snakes are very good at "hide & seek" (especially if your boa is a lot smaller than mine was). I had no trouble guessing where she went, & she even hissed up a storm at me when I had to take her out- she was so happy with her new "cave" & it was hilarious. So just be ready for that, and better yet- prevent yours from disappearing. Don't trust a snake to stay still, ever. They instinctively wait until they're not being watched- as if we are predators- before they take off.
