Nothing wrong with that. Sometimes things happen that we can't explain. Either way the deer died, and you put it in the right spot, so it is no fault of you or the bullet. Just how things go sometimes, and 100 yards is not that far. I had an elk go 400 yards with a 385 grain Hornday in her chest last year. The bullet stopped just inside the hide on the far side, taking out both lungs.
Later,
Marcial