Next time it does it put your hand up on the visor and see if that is rattling. I find that mine rattles around a bit when up and it sounds like it is coming from the A-pillar, but it is just very close. The visors are pieces of ultra cheap plastic, so not sure of a fix. I did think that maybe I could get some nice ones off a wrecked Grand Cherokee or something, but right now I just deal with it. Sometimes just knowing where it is coming from slows down the OCD.