As some players are beginning to notice, Blizzard has apparently been doing some changes to World of Warcraft's Season 3 armor sets.

The more notable of which were reported tweaks to the paladin's Vengeful Gladiator's Vindication set, which saw a strength boost to hopefully increase survivability. Vaneras dropped by the official WoW forums to confirm the changes:

It is true that the Season 3 retribution set has been changed. We're removing the Armor Penetration and Spell Damage that was being added to season 3, and moving those stat points into Strength.

Hopefully these changes should be visible soon with an upcoming PTR patch.