Perry's gotten a funny habit lately. He'll be laying in his kitty cube in the evening and he'll start to give a low growl. That "don't touch me, I'm in my safe zone" growl. But he'll do it when no one's there threatening him in any way.

Often when he starts growling I'll look around to see who's bothering him and find Marco in a cube on the other side of the room and the cats snoozing on my bed. No one is looking at Perry, no one is near Perry. He's not dream-growling, he does it fully awake - occasionally he'll stick his nose out of the cube. And keep growling.

I'm wondering what i can attribute this to. It doesn't seem to be a physical problem - he's been just fine recently. What i do know is that he tends to values personal space *a lot* and hates to be approached by other animals when he's laying down. Occasionally he'll snark, especially when someone shows up near him by surprise (mostly Marco and occasionally the cats, never to people). He'll let the cats have full dominance otherwise (he will rarely even walk past Tim). The only time he'll snark at Marco or other dogs is if he's lying down and they get too close or invasive.

I have no idea what to make of this. It seems harmless enough so far but I have a feeling that this might escalate. Any thoughts?

I would see if you could distract him- to see if he is indeed "seeing" something versus just warning the world that he wants to be left alone. Just a thought.