New Dendrobium - Mold on Bark

[akorchid]

Hello. I have a fine white hairy mold growing on the bark of my dendrobium. A few told me to repot, but I've heard you shouldn't when the plant is still flowering. The plant is obviously okay, as a new shoot is growing taller each day. But, I'm afraid the mold will give growth to pests or damage the plant. Should I repot, or is it safe to wait it out?
If I do repot, I'm not sure which type of mix to use. Is Miracle grow orchid mix alright? Do I need something specific like volcanic rock, perlite, fir bark? I'm not sure where to get these things locally, so some specifics about repotting would help before I start searching every store in town.