Pillow Mobs

When spawned, it is a perfect 6 x 6 square. I've been to every town and I have accounts that it is also a 6x6 square in other towns. I was also there when they actually spawned. Because it is late where I am, there are no players are nearby to provoke the mobs into moving around. There are no mobs in the middle of the this 6x6 square and every kill has been accounted at 36.

I've seen it several times, one time there was a black warrior hanging out far from the 6x6 square. If you'd like, I can try to take a screenshot. And yes, these times were when there were no other players that could provoke their movement.

Edit: Starting to doubt myself now, sorry for any trouble I might've caused.