It sort of is and isn't. They could be loosening up a little at the root, but it happens. Mine are mature to the point where they'll never come out. And the roots still happen to feel loose once in a while, but if you forget about them for a few weeks or so they'll feel tighter the next time you touch them.
It could also be that your hair is always growing and as it grow in it creates straight hair by the root. So i'll feel like they are coming undone, but really they are just growing. My locks grew super fast once they matured, so if yours are anything like mine, it'll seem like the roots are loosening, but take a look at how long they were a month or 2 ago and you'll notice that it's really just new growth that hasn't locked up yet