There are zones in EQ that originally had the modifier. They then added more zones that had mods in that patch. Took them 5 years before they started adding hotzones thats rotated. Can see the list here:
http://everquest.allakhazam.com/wiki/eq:hotzones
Also need to check and make sure those zones dont have that xp mod on p99 cause it wasnt patched in til after velious release. Will get Dald on that.