Dried mushrooms

[ojisan]

What does it mean when dried mushrooms start turning white?

I have dried shiitakes and porchinis, stored airtight well over a year, turning white. I realize that I've held them too long, but I've been using them, so I assume they're safe to eat. But I wonder if there any concerns or reasons why they should not be eaten.

[Panaderia Canadiense]

I've always assumed they're "blooming" some other fungus, but I continue to use them so long as they still have a good smell. I haven't had a problem yet - and the dried Suellius mushrooms I use are very prone to blooming even when they're quite fresh, and if I turfed them the minute I saw the white stuff I'd never have any in the pantry.