Azaleas and Leaf Gall
This is Exobasidium leaf gall, which is not uncommon in wet springs. It does not hurt the plant, and you can do your normal pruning right now if you need to.
You could just pull them off and dispose of them now too, which will make them less likely next season.
Here is our page about them: http://extension.umd.edu/hgic/azalea-exobasidium-gall-shrubs