I hadn't heard about anything like this happening, but when I got my yorkie, he would sleep on the couch when I was up working late and he would snuggle in next to me with his head buried in between me and the couch. I picked him up and he was limp. I panicked!
I put him on the floor to check if he could stand (this happened with another dog of ours - food poisoning - and she couldn't stand or register that we were even there). He woke up and was standing just fine.
Sorry for the long post, but I don't think you have anything to worry about. These babies are tougher than they look and they won't lie in a way to cause danger to themselves. Their survival instinct is much too strong for that. I know it is scary, but the chances are very, very slim for him suffocating. He will make you up if you lie on him.