I think this is a funny little quirk. Have you ever tried to look dead? I enjoy acting, and I can tell you, it's HARD! You really have to work on it to breath so that your chest doesn't rise and fall. I tend to excuse these types of things in movies on the grounds that I can sympathise with the actor. Of course, I understand that other viewers don't share my viewpoint, and respect that. Okay, maybe they should have found a real dead person to play the corpse! Sorry, just joking.