It went under the radar until I realised while killing zombies at my mob spawner, that no zombies showed up with any form of armour. Occasionally a shovel, but no armour at all, what so ever.
So I surfaced and went to creative mode to fly over terrain at night and noticed that neither Skeletons or Zombies had armour of any sort, the skeletons also did not have enchanted bows.
I am not sure if it occurred before the pre-release or not as I only just came back up for air to get XP for new weapons and armour.
That may depend on local difficulty. Stay a bit longer in that area and see if the spawning changes.