It took me a while to figure it out. Since I bucked the logs up, I knew that nobody was screwing with my head. I cut a 20' log off (which was the butt cut) and sawed it. The next log was another 20 footer, which I sawed. The third log was 16'. I had sawed about 4' when I hit the post. This put the T post at least 45' from the ground. It was broken off beneath the bark, which is why I didn't see it. It was driven in rather than "grew" in. You can see the torn wood fibers around the post.
Bottom line. When the tree was cut, it fell across a fence which drove the post into the tree. When the skidder hooked up, the post was broken off inside of the tree.