Nope, just helps you mine when your in a rut, like when tin is green and iron red.... lets you get to the next level node so you can acuatly raise your skill.
once again to be clear, higher level mining skill dose not affect drop, just like higher level herbelisum dose not affect drop, or higher level skinning. They simply allow you access to items earlyer(in the case of skinning whrere mobs over 60 are present, it actualy allows for the skinning of preivuoulsy unskinned beasts. but dose not affect the drop, that is determined when the node spawns.