After you install your dreads, they have to loosen up before starting the process of tightening up again. The roots are the first thing to loosen up, and it is completely normal. You are supposed to have an inch to two inches of loose hair from your scalp to where the hair is dreaded. That should be what is loosening at your scalp: just hair that is unfrizzing at the root. Normal and healthy.
Re-backcombing your hair causes more problems and is damaging. After installing your dreads, there should be no need to backcomb them again. And palm-rolling is pretty much useless unless your hair is wet (and then it is great for helping get water out of your dreads, and keeping them in shape while they dry). Rubber bands seem like they keep the hair together, but they actually prevent the hair from moving around… which is what it needs to do to start tangling. So, rubber bands may seem like they are working now, but they are actually hindering times maturation process.
If you are worried that your roots are longer than what they should be normally (again: an inch to two inches from your scalp to the dreaded hair), then you can root rub. I find that root rubbing works best the day after I wash my hair. It is clean and completely dry. Sometimes I even root rub the same dreads two days in a row. Day 1: Wash and Dry. Day 2: Root Rub the roots of the dreads that seem a little long. Day 3: Root rub the same dreads. The next time I wash my dreads, I notice that those dreads are closer to the scalp and tangling nicely! You don’t even have to do your whole head all at once. I usually just do a dread or two at a time, when I notice they have long roots having trouble tangling.
I hope this helps!