I say it was just a bad day.
I'm sure the book will be a good read for you then.
And don't feel bad about the bad day. I had a topic on here a while back that was just about the opposite of your post. I was shooting at the field archery course at 50 yards. I then went to the 3-d course and was trying to shoot at a deer target 20 yards aways. The deer was down a very steep bank though. Not only could I not hit the deer, I couldn'teven focus on him. Next dayI went back to the deer target and couldn't miss.