I have experienced the same thing. So you're not alone!
No kidding there I was.
I had made a move on the inside of the pasture. Some small pines. The bird was in the hardwoods. Of course there was a fence. For whatever reason he didn't come into the field. I could see him behind the trees. He strutted up behind a big split tree. Came out of strut. I put my scope on his head. Which was in-between the trees. I really didn't give it a second thought. He was in range. I squeezed the trigger. Boom.
All of a sudden I saw a Gobbler fly off. I laughed to myself. Thinking it had to be a second bird.
Once I got to the tree. I looked behind it where the bird had once stood. NOTHING! I looked at the front of the tree. Perfect pattern.
The only explanation I can think off. He moved his head during my trigger squeeze.