You should be able to tell when they throw up, if it's like mine. Hoju will bop his head like he's going to share some seeds, but then he sneezes a few times, and then shakes his head rapidly spitting up seeds. Sad to see, but definitely not the normal food sharing behaviour :P
I'd imagine he'd be ok if he had a nice warm spot to dry off with no drafts, which it seems you've given him already.