Congrats on your new noodle!
I'm glad she's already settling in so well for you.
I agree with Bogertophis on temps and monitoring the decor for any holes she can get stuck in as she grows. I've had to try getting some baby corns out of a fake tree log once when someone at the big box store I worked put the wrong decor in the reptile habitat while I was gone. =_=;
She's probably warming up to where she needs and then moving away from the heat to the more comfy hide. BPs are very shy so something about that spot makes her feel secure enough and is a better temp for her. If you bump the temps down a bit she may stay on the warm side more.
Humidity is tricky. Covering the top will help for sure. So will the moss. The thing about misting is that it is such a light coverage that it will dry quickly. What you would want to do is carefully pour a bit of water around the substrate and stir it a bit so the deeper layers can soak a bit more in and retain while the top layer gets dried out. It's very easy to oversaturate though so you would want to do a little then check back later if you need to add more.
Also, double check the heated hide just in case with a good temp gun. Sometimes probes won't read quite right...and you want to make sure the glass above the pad isn't too hot, that way if she burrows down into the perfect temp top of the bedding she won't burn herself on the warmer glass under it.