I understand that it doesn't pop overnight. So I'm not sure what you considered as Hex. But I've had many cases of hex with a few of my flowerhorns. Shedding those white stringy poop look is a natural phase, but if very often and being long and stringy may very well be the beginning stage of hex.
Shedding white poop often and still eats, then this may be a case of needing to deworm your fish.