This is Adam's write-up I'm talking about...
http://forum.8ballpythons.com/blog/?p=5
It says it right there that it is present in "each and every spider, some more noticeable than others". Coming from Adam who has a humongous collection, it has a lot of weight.
I don't really mind the wobble. Mine is very slight and is only noticeable when he's holding his head up for too long. But even if he has more than that it would be fine as long as he's healthy. I was just curious if bumblebees and other spider-based morphs have it as well.