Yep, next time you get something that looks like mold to you, take a photo and post it here for us to see. Very likely what you are seeing is a larger yeast bloom. And in any case, stirring it back into the mix, whatever it is (even if it IS mold), the lactic acid bacteria (LAB) will consume it and produce more health-giving LAB babies. Don't just take it from me or others here (though we do have some experience with this), the fermentation guru known as Sandor Katz has written a couple excellent books on the subject. His tome, "The Art of Fermentation" also includes color photos of these sorts of things.
Anything white and fuzzy is most likely yeast. Brown, black or green would most likely be molds. And unless you live in a hot and humid locale (ie, the deep south of USA), it's not likely that black mold grows in your location. Most "black molds" are actually very dark brown molds (if you hold it to bright light), according a veteran plumber who worked in the Seattle area (humid but not hot) who had seen all kinds and lots of mold over his 30+ year career.
One thing I do to keep more oxygen out and reduce the chance of mold is to cover the FF with a plastic bag. Mold isn't so awful like we've said, but my FF is so thick it is not stir-able. In my case, it's not a problem, because I don't stir mine (I use a slightly different fermentation method than most folks here). But regardless of your fermentation method, a plastic bag on top will keep oxygen loving molds and yeasts from getting too out of hand.