Are you sure? Blitz doesn't centre the origin of loaded meshes, AFAIK. Maybe it's something the exporter in your modeller is doing!?
As a last resort, you can always use PositionMesh/FitMesh to re-position the origin to the left side of your door.
As a last resort, you can always use PositionMesh/FitMesh to re-position the origin to the left side of your door.