Should dry salami develop green mould? I recently (5 weeks ago), purchased a set of dry salami from a food festival. I kept them in the plastic bag that they came in; however, when I recently checked them, they were completely covered with furry-looking green mould. 

My understanding of dry salami is that it is supposed to be able to be kept for (in some cases) several years without risk. So I am confused, What could have caused the mould growth that I experienced?
Take the salamis out of the bag.

Are they complete sausages or has it been sliced? Whole sausages should not be kept in a plastic bag without desiccants even if it's just a ball of paper towels.

Sliced salamis shouldn't be kept for more than a couple weeks.

If they are whole, don't be fooled that you can just wash the skin, molds grow tendrils into its food, not unlike roots, so don't risk it.