Dean's out for a walk when the rumbling happens; it's enough that it makes him stumble and fall, hitting his back on a tree as the leaves shake around him. The rumbling stops, and Dean stands there, eyes wide and uncertain as he waits to make sure it's not going to start up again. And then he gets the hell out of there, hurrying through the woods before they have a chance to fall down on his head.

Once he reaches the edge of the woods, he tries to spot what he was sure was a crashing sound. If the freaking diner caved in again he's going to be so upset. He's so proud of that.