Truss Roof you say. That sure looks like a ridge cap and a 4 to 5 foot span of sag at the ridge. I've never seen the gusseted ridge of a truss sag like that before...trusses are 24' oc aren't they?

Are these scissor trusses? If the span of the sag is 4 ft or more you might want to investigate further...broken truss maybe???