Health question about betta fish?

I don't think so. Usually fuzzy bits off the fish (not part of the body/scales/fins) are ick. Ick can come in different colors. There's standard treatments for it I believe it's a bacteria. There may have been enough of something in the food to encourage bacteria growth in the water, resulting in this, but sometimes it's just something that happens. Try googling 'fish ick pic' and see if the pictures match what you're seeing on the fish.