Spray or dab a little pure Listerine* in there, then let dry.

* or any other compound that contains the antifungal ingredient - thymol.

If one side has taken, good. But do be careful if you are going to wrap it back up. The joint is extremely delicate at this point and will easily break. Probably best not to touch or stress it whatsoever, meaning do not wrap it back up.

Left to itself, the mould would probably not really hurt anything. Exposed to the air it should stifle enough.