One thing you can do is spray them with Serenade, which is Bacillus subtilis, a bacterium that destroys mold. You may find it in garden supplies, or can order it on-line from Stark Brothers Nurseries or other sites.
Ideally, leaf should be stored at no more moisture than low to medium case. If you allow it to dry so that it is somewhat noisy when handled, but still flexible, that should be fine.
Bob
NOTE: Mold makes tobacco taste crummy. Generally, only black mold (Aspergillus niger) presents a significant health risk, and then only if chewed. The black mold can produce aflatoxins that damage your liver. Aflatoxins are not present in the smoke of burning tobacco.
With blue or white mold that is minimal, you can sometimes wipe it off and save the leaf. I usually toss leaf with black mold, or any leaf with a lot of mold. Sometimes only the stem is moldy, and the leaf can be saved by simply stemming it.