Some new changes were added to the patch 2.4.3 PTR notes. Among them are the entries below concerning warlocks and mages.
Mage
* Frost Armor, Ice Armor, Mage Armor, and Molten Armor are no longer Magic effects and cannot be dispelled.
Warlock
* Demon Skin, Demon Armor, and Fel Armor are no longer Magic effects and cannot be dispelled.
This change is obviously a PvP one and is probably not much of a big deal. It seems strange that these armors can no longer be dispelled since the effects they give are indeed magical. In this sense, there's not much difference that these armors have with the Inner Fire ability that priests have and yet only the mage and warlock armors have this benefit. Not all armors are mere armor giving effects either since fel armor actually gives the warlock +spell damage and this is something that an opponent would probably want to get rid of.
Perhaps this change is in line with the shaman totem change that was announced some time back wherein the act of dropping totems is in the physical school so even if the shaman is spell locked he can still cast totems. I never really thought of being able to dispel these armors as imbalanced but I'm not really complaining.
As always, the latest PTR patch notes can be found here.