m0useanswered grow question 3 years ago Fungus gnats live mostly in the soil and only come out to breed and be annoying. They do not eat leaves, they eat fungus that grows in the soil and inadvertently sometimes the small new roots the plant produces. You need a massive infestation to cause real damage and stunted growth. I use nematodes "pod poppers" to take care of them and yellow sticky traps, this combo kills them in two parts of their life cycle larva/adult. amazing product.
Keep an eye on it, might be an isolated incident, plants looks very healthy and nothing to worry about. I've also had some mutated leaves pop off every now and then.