T13 Armor Broken?

[:1]Recently I aquired a T13 Tier Leg Piece and today I tried them on, but no matter what I did, the armor was lower than my T12 legs. It said it was a gain of over 100 armor, but it actually lowered it. My T12 legs don't have any particular armor bonus to them. No enchant or anything like that and agility doesn't grant armor nor dodge. So what's going? Yes, the T13 legs I purchased didn't have gems or enchants, but that shouldn't have effected the armor.

I switched to Balance spec and again, the T13 legs had less armor than the T12. Am I missing something here? Is there a hidden T12 bonus to armor or is there something wrong with T13?
You broke your meta gem which needs 2 yellow gems.
T12 legs -> 2 yellow sockets
T13 legs -> 2 red + 1 blue
/smiles

Meta Gem activation, hun.
DAMN YOU META GEMS!!!!!

(I've done this too when getting new gear, sometimes I wish I had an addon alert)
Oh. Well, damn, looking at T13, there's only one yellow socket. So many reds. Kind of sucks I'll have to use a topaz in a red socket...