Attic Insulation

[JIM MURPHY]

Viewed an attic today that was 20 years old and the roof was replaced an year or less ago. The insulation had a dark film on it. I did not touch or disturb it thinking it could be mold. Your thoughts? Picture included

Jim

[H.G. Watson, Sr.]

I'm guessing its dust coming in with the wind through that gable louver.