My carpenter just installed four sets of bi-fold louvered doors. They are beautiful, but they don't stay flat. They fit (plenty of room on all sides), and they are plumb (I made sure of that!). But the joint in each set of two doors where the hinges are doesn’t stay flat. I can push it flat, but it immediately comes back out about ¾ inch. So the four sets have a slight "accordion" look to them. It seems to be something with the hinge design, I think. Anyone have any experience with this and how to remedy it? They are Relia-Bilt.