In tonight's hotfixes, Blizzard announced that five mounts now have greatly increased drop chances. These mounts are obtained from world bosses several expansions ago that were infamously known for minuscule drop chances.
Earlier this week, some of these were part of a loot issue (now fixed) which gave Evokers an abnormally-high chance to loot these rare mounts.
WoWhead ArticleThe drop chances for Son of Galleon's Saddle, Reins of the Heavenly Onyx Cloud Serpent, Reins of the Cobalt Primordial Direhorn, Reins of the Thundering Cobalt Cloud Serpent, and Solar Spirehawk have been greatly increased.