April, if you haven't got the paddle separated by now, I think the obvious solution is soak the paddle in fresh water and maybe hot water. Most likely salt is causing it. Paddle gets wet, salt water infiltrates, dries in the joint as you paddle and locks it up. You can put a plastic bag over the joint area with elastic bands or tape and fill the bag with water over the joint if you don't have a better way of soaking it. Good luck.
The Connyak BBS