It can sometimes be difficult to judge how much you've had.
I was at an awards do this spring (I won an award). I KNOW that now, post menopause, I can't drink like I used to, so I carefully monitored how much I'd had (didn't want to be dancing round the room with my pants on my head). Went back to the hotel, moderately sober, chatted with my OH, went to bed...
...and promptly had to get up and spend all night on the bathroom floor with my head down the toilet. Anyone who'd seen me at the 'do' would have said I was mildly tipsy, I had moderated and tried to keep an eye on my intake, and yet...
It happens. If it's a one off, let him have this. Life with small children, as someone above said, can be relentless. I'm sure you have time off now and again, OP, even if you don't get upchucky drunk. It's life, he's hardly been arrested and is phoning you to bail him out from a city 400 miles away...