Weird shading error on mesh I was making a hand in Blender when something weird happened. I extruded an edge, and the new surface was discolored:    



Making additional extrudes will cause the new faces to be discolored as well:



Deleting the new edges and extruding again yields the same result, but extruding from the thumb(which is the same object but isn't connected to the main hand) will color the surfaces normally. I've tried flipping the normals, but everything seems fine there. No matter how much the vertexes are shifted around, it's still colored differently. Any ideas on how to fix this?
Found the issue. Somehow a bunch of vertexes got duplicated, and that made an indent in the mesh.