I've actually got that only on special places, specifically the cowling that opened, the gear doors, the inboard cannon pods, and this one prominent line on the inboard leading edge. The rest of them are not like that. I think it accentuates the parts that opened or were most noticable. I'm open to removing it, however.
EDIT: I may be thinking of something different. I'll go through and tweak layers to see what I can get.