That snake looks like it was healthy to me, not really skinny enough to die from starvation. I'm guessing it was just a random death. When breeding lots of animals a small percentage of them just die from random causes, heart problems, etc... I think it's just to be expected. If multiple snakes start dying or if you see them look skinny or discolored then you have a serious problem. Otherwise I wouldn't worry about it, just a sad part of nature.