Affects Version/s: Snapshot 13w07a
Fix Version/s: Snapshot 13w09a
Creeper doesn't react at the Cat if there is another Cat (not visible for Creeper) within 3 blocks below it.
Most likely Creeper checks Cat presence starting from below coordinates and getting locked at first found Cat.
At the first screenshot, 2nd and 3rd floor Creepers doesn't react at their Cat unless you kill Cat below.
At the second screenshot all Creepers act properly.