I have a two year old who has lived with us since he was two months old. He gets along with the other cats in the house. Twice this month he has looked at one of the other cats we have and acts like he doesn't recognize him. He watches terrified from the other side of room. His tail puffs up, and he won't stop watching the other cat. The other cat just sit relaxed across the room. The other cat finally walked up to him and loved on him the other day. After the other cat did this, our little male relaxed. What would cause this? I would understand it if the other cat was in a fight or play stance, but this keeps occurring randomly. One time the other cat was just sitting relaxed, and the other time the other cat was relaxed curled up. I think he is recognizing us, so I don't think it's a health problem.