Mmmm he doesn't really have... fangs... per say.... They are very, very tiny teeth. I would definitely not recommend you every try inserting tongs into his mouth again if something like that happened though. It could get worse. How long did this go on for? If it hadn't resolved itself in a reasonable amount of time I would have gone to the vet. I'm wondering if his jaw may have gotten stuck awkwardly?? They usually yawn to adjust everything back to normal from all the stretching after they eat. I haven't heard of a snake getting it's own teeth stuck in its mouth, tho... I don't really know, I'm just guessing to be honest about the jaw theory. Is there a lesion in your snake's mouth? Maybe you should take it to the vet?