Hi Michael,
Not to scare you, but can it be a fungu?
You have done a right thing by keeping them separated
when they're not used. But, if I may suggest you, don't
keep your gadgets in the bag.
I left one level of my closet/cabinet in my bed room empty,
put a 5 Watts lamp inside, and put all my equipment there.
Regarding that the heat may affect them, I keep the equipment
as far as possible from the lamp. So the lamp is used just to
keep the cabinet/closet dry.
It works. So far, after 5 years, no fungus grows in my lens.
I have one lens, bought second, with few fungi inside.
The grow of the fungi are stopped by keeping the lens
this way.
Hope this may worth...
---
David
