That could be a silk from a worm. Be on the lookout for catervermins, caterpillars. When you see moths flying around and landing on your plant start looking for munched leaves, or poop that looks like pepper. The poop and injured tissue feeds botrytis. They like the tops and colas after hatching. They lay small round eggs in clusters on under side of fan sometimes sugar leaves. They hatch and in 2-3 days make it to your colas. They can even drop in from up high from near by trees. Rub em off, or spray with appropriate treatment.
If already in the cola, cut out whats been munched or pooped on and watch the site for mold.