Oh okay then well gross to the max.
Hm. I have never had to deal with mold- with any luck someone more experienced will chime in, but your real problems start when the mold attacks the ROOTS, and I have a hunch that the type of mold to be growing on coco fibre isn't going to want to go after the roots. From what I understand about soil fungi- the mycorrhizal sort- there are fibrous types that would somewhat fit your description, except for the slimy bit- and they aren't harmful; rather, they process dead organic matter and make it nutritionally available to the plants.
So I think that until you get a better opinion on this, you should focus on monitoring the plants' appearance, and just generally keep your system as clean as you can (remove dead leaves, keep air flow moving across the surface of your hydroton)- which are things that you should do anyway. My hunch is not to be too too worried about the mold ...