I'm curious too. I'd venture to say he's okay but don't want to steer you wrong.
I know Alphy's breathing when he's deep sleep is like non existent. I've freaked out many a time. I wake up in the middle of the night and put my hand on him, if I can't feel him breathing I scream Alphy. Couple times I've grabbed him screaming his name while he's rag doll limp and finally he snaps out of it and is like what's your problem lady? I was sleeping.
other times it's like he's panting, but I think he's dreaming.