I would remove the mold, it might effect the pH (depending upon the mold type). Remove the peat moss you put on top of the topsoil and hydrate fully with water, let it soak in well for a few minutes or longer. You want the hydrated peat moss to drip water when squeezed. Then add the peat moss back and mix it all up well. Once vented, mold shouldn't occur unless you feed the worms in excess. Just my opinion. Good luck.