Various kinds of fungus will form on newly planted aquarium plants and on pieces of driftwood and anything else in a new tank. It's natural from what I've observed in my tanks and is caused by the fish, plants and bacteria working to settle in the new water conditions.
I found that Ramshorn snails put into the tank, will use the fungus for food. I put a few of the Ramshorn into my tanks and the fungus was gone in a few weeks. Don't forget large, frequent water changes. These are the most important requirements for stable water conditions.