Glenn,
I believe it comes from the theory that the space between the eyes is about the same size as the first curve/exit in the intestines right as it exits the stomach, before it is digested much. I noticed that during a necropsy and since the crickets leave the stomach in a compact like capsule, anything larger could get stuck there.
Something else we noticed, when laying or basking flat, that curve is very noticeable and sharp..... but when straight up and down, it is almost non existent.....possibly another reason that very young dragons, given the choice, seem to prefer to bask and sleep being straight up and down. It may very well assist them in moving foods through their digestive tract.