That will happen if you top off w/ tap water. The minerals (in the water) sometimes will accumulate around the leaky seal. Another Poss. is there was a piece of trash circulating, and got caught under the lip of the seal. I would think it is perfectly safe to run it, and just keep an eye on it. If it was trash, and expelled... No Worries! Minerals will wear, and the leak will re-appear.