The paw pad variety of this is called Footpad Hyperkeratosis. Hyperkeratosis runs in bloodlines and results in severe digital hyperkeratosis (overgrowth of crusts and crud) by 5-6 months of age. Once again, not life threatening, but needs to be addressed for their comfort and your peace of mind.
For more you can refer to this site.
http://theblissfuldog.com/dry-dog-nose/