If you've seen the pictures of our frame, there was a point where the centre posts were just floating... the roof beams not having been lifted at that point. Striking a post with your hand at that point made the whole post vibrate for a few seconds. Once the roof beams were in, the vibration was reduced, and once the rafters were nailed on it basically vanished.

The first thing that most first-time visitors to our house do is to whack the posts before commenting on how solid it is. This is mildly disconcerting, but also very satisfying.