Hi brydon,
i don't think it is normal for the leaves to curl up like this, but I don't know either what is causing it.
the only thing I can tell you is what i did when my Accuminata Sumatrana did the same. I cut the leave at the leave mid rib, verry carefully, without harming the new leave inside. then I removed the curled leave part to free the inner leave. It doesn't gets the beauty-nanner-award, but it works cause the new leave can grow freely now. I had to do this twice (cut bad leave - good leave - cut new bad leave - 2 good leaves) and now it's growing perfectly.
Grtz Marguerite