Ah, I see. This is called a "die rotation error" (sometimes die axis error) where the obverse and reverse dies are not the exact same degree of rotation. I'm sure this is just human error and not setting the dies up correctly when putting them in place, although I've heard of dies rotating once they've been in use for a while. Not actually as common as it might seem, and I've seen some full medal style rotation errors (180 degree turn) sell for a good couple of hundred pounds. Pictures would be good, you don't necessarily need to show the degree of rotation although you can achieve this by taking a picture of the back of the coin with the front of it facing a mirror. That way you can see both obverse and reverse and if you keep the side facing you as upright as possible it gives a clear indication how much the other side has turned. By the sounds of it, the rotation is only minimal, but you might still get more than a standard 'worn' 1918kn penny!