my reasons for repotting was fungus on the soil surface of my nep. Maybe that's not a problem.
I have had this on orchid bark from time to time, and it was never an issue.
The "fungus" looks to be a type of mushroom mycelium , although I never had enough of it growing on orchid bark to have any mushrooms produced in the pots. I have however, seen others have small mushrooms growing in their orchid pots, especially some orchid nurseries and in the pots that were exposed to a lot of moisture.
Unless it is all over, I wouldn't worry too much about it causing any problems.
As a side experiment, you might try taking it and keeping it moist without too much light, and see if you can get it to fruit (produce mushrooms). It would be interesting to see what type are produced.
Nice pictures of the mycelium!
Experience is the best teacher. At least it used to be.
But then, common sense isn't so common anymore, is it.