Well, he got that out of his system, didn't he? The sicker you get the first time you get drunk, the better off you will be later on!!!
He is a wonderful young man (can't say boy anymore), but I would sit him down and explain how nervous you get if he doesn't let you know his plans on coming home or not. You might want to add that even if he is not drinking and driving, other people are, and you need to know where he is spending the night.