It's because of stress. If a little snake is in a large open area, it is nervous, that's of any specie type. In the wild baby snakes usually hurry from one hiding place to another. I think if you have a lot of stuff in the cage, the snake will not get stressed because it won't be as much of an open area. If you had two or three hides a climbing branch and a waterdish in that size of cage, your snake would undoubtedly get stressed because of the large amounts of space in the enclosure.