I will usually see my newborns try to eat some coir when I first put them in the enclosure, but they usually stop trying quickly. Perhaps increase the food amount so he eats food instead of dirt.
I first noticed it when he became picky and didn't want to eat the spring mix and greens I was giving him. I had kind of buried his humid hide so it was more like a burrow. I saw him one day on top of the hide trying to eat the coir.
They are curious creatures. Mine will try to taste all sorts of things when I put them outside - leaves, rocks, sticks, bugs. It shouldn't hurt him, so maybe it is just a passing fancy.