Ya the mites are from the petstore where you got her, the mites will hide under the edges of the snakes scales, and under the edges of the eye socket as well as the thermal pits on the snakes lips. Im sorry to tell you but that petstore is very obviously infested with mites, they are not easy to see and will go unnoticed if people do not look for them very hard. They will not come home on a mouse thats for sure. I guarantee most of the reptiles in the store will have the mites on them and in their cages. Plus the stuck shed in the picture looks bad enough to actually be two stuck sheds, meaning the petstore probably neglected the snake during its last shed as well... Besides which a ball python should be misted daily to maintain the humidity in the enclosure, not just during the shed...