As we dry out the walls in a new home, I've noticed that some studs have black streaks of mildew on them. I'm sure this resulted from the boards laying in stacks outdoors during rainy weather, not since they were put up. They are bone-dry now and we're ready to insulate. Will these boards be a problem in the future? Replacing them would be very difficult - they are on outside walls, already wired with power and low voltage wiring and passed framing inspection.

They should be OK but if you are worried about mold in general just mist them with a 1:4 mix of bleach and water.