Spraying Bacillus thuringiensis israelensis (BTi) every 10 days should prevent any mold, and fungus gnats from ever appearing again. Use this align with sticky traps and good watering pratices to minimize te risk of infections. Also, do fix the infestation, do not ignore it just because the plant looks good, it wont look good if the infection develops more, and shit will probably be happening underground to, su thats why you should always take care of the infection at first sight. Most larvae form of of these insects damage roots and disease the soil, wich will only show up as weeks past. Even if you cant exterminate the infection, keeping her in control will come a long way, and BTi doesnt cause resistances in bugs. Bti is good because it can be used as a preventive method aswell as an active method, on veging and on flowering, without any harm done to the plant or the smoker. Is also microbes, so they are organic and disappear really fast from the plant, specially when exposed to light.
Hope it helped by giving another solution. Good luck!