Highmountain Tauren Heritage Armor

I leveled a Highmountain Tauren from 20 - 120 but did not receive the Heritage Armor. I did not get the Achievement, Heritage of Highmountain, either.

I did not use a level boost; I did not change race; I did not use the refer-a-friend boost; and I didn’t even use the XP boost gems.

What did I do wrong?