Simon - a great post.
Not sure if it is age related, but I have also shot wrong targets in the last 2 years. One at the Far Coley GP last year and one at the Tawd Vale GP this year. Before that - it had never happened in competition.
I can also sympathise on the needing a pee around the course - another age thing
A real shame to lose out in such a way - especially on the very last lane when the hard work was almost done.
I hope you don't dwell on it for too long and you can put it behind you.