Hi there!
I've found this bug when playing around on my new toon.
Everyone knows that lvling mining up is a pain in the ass. I myself have skilled it up when I was 70.
Anyways, when you find a vein to mine, mine it once. Then you go kill 1-2 mobs, and skin them if you can, then you simply walk back and mine again. Then you should notice you get 2 skillsups for the same vein! This is very usefull when there ain't many veins around.
I'm not sure if you have to kill some mobs, skin something or just wait some time, but maybe it's all of them and it wont hurt if you use your time killing and skinning instead of dancing .
Hope this is as usefull to others as it has been to me