I think you are correct, carbon doesn't have a memory (unlike metals) but it will take a set. I don't have experience with carbon catamarn masts, but in windsurfing, if you leave a sail rigged too long, the mast will take a fore/aft set. The solution is to rotate the mast 180deg and then re-rig to bend the mast back the other way. So, using that logic, you could probably disconnect/loosen the diamond wire on the concave side of the mast, tighten the convex side, and let it sit there for a few days to bend it back the other way.

sm