Being asleep in bed is one thing, and actively expecting something to jump at him with greebly little tentacles is another. Popp is grumbling at relatively low volume on purpose, and does possess an attention span. Maybe it's a rabbit? No, a rabbit wouldn't be following him, would it? He whips around-

"Aha!"

And then runs for it as fast as he can. He's a team player, killing it was Mithrun's job, and he does remember that they tend to explode.