I've not had a hatchling with this issue- personally, I'd wait & see if it self-corrects, but it's a concern for sure. In an older snake, trouble retracting the tongue can be a sign of a mouth that's sticky with an infection- maybe this snake has some "egg" that dried a little in its mouth- I would try getting him to drink to rinse out his mouth. I assume this snake has no other obvious neurological issues (trouble moving around)?