im sure its nothing you did. it sounds like she was in perfect health. and as others have said, sometimes they just spontaneously die. dont beat yourself up about it
That is true.
However, when a breeder has animals that he has sold/given away dying and siblings in the same clutch dying... I would look for answers.
This could be nothing or it could be something at least we could learn something.
*getting back on track here*
"Price has very little to do with QUALITY. Quality stands on its own merit and doesn't need a hefty price tag to prove its worth."