Our supplier says the logs will not settle (shrink). But many books say they might. If the ones beside the door do settle, then... the door post will not shrink (in length). That would be a huge problem.
So there's going to be ½" gap over the door. So that the wind doesn't blow through, we make this spline in the top of the door frame.
That spline is going to slide up into this slot in the bottom of the log that goes over the door. The chisel you can see in the picture is called Slick.
There's the log over the door with ½" gap, ready -- just in case.