Seeing fungai (mold, mushrooms) is a good thing in a worm bin. Add some rock dust (like Azomite, glacial rock dust, soft rock phosphate, etc) to increase the fungi levels in your final worm castings.
i feed my worms moldy food all the time. actually, out of neglect/laziness i tend to let the scraps sit in a container or bag and rot before i put some in the bin. in the ideal situation, whatever you feed your worms should be chopped up really well/blended so they consume it much faster. if the worms aren't actively eating it right away, most things have a tendency to mold in the bin anyways.