Bukkit

Sometimes the ore veins spawn in front of players. This is a rare occurrence that usually happens for miners down underground wandering around in a cave split by the border between two COV areas. The current trigger mechanism looks only at the current position of a player. As soon as he or she stepped into a new area, the vein population is triggered.

A quick solution here is to trigger the vein population when players get close enough to the next one, "close enough" being controlled by a setting that dictates the proportion of a COV area.