Wow! One of my compasses reversed as well this year, and it really confused me at first! I began to doubt if I remembered the rhyme "put the red in the shed" correctly until I had a chance to place it side-by-side with my other compasses. I don't know what could have caused it but it was a really strange experience. Luckily I had my GPS with me and I also had a pretty good idea where I was supposed to go.