First of all, Ball Pythons come from a region in Africa that is very close to the equator. Therefore, there is no hibernation occuring. Most of the time, these snakes are breeding in the winter, and laying their eggs just prior to Spring, and hatching throughout Spring. Most females will seek cooler temperatures when their follicles are developing, and hence the winter breeding.
Also, many people believe that the breeding season has evolved to coincide with the rodent boom that occurs in late Spring. More food makes it easier for baby snakes to survive. And survival is instinctual in all species, meaning mom is doing what she can to ensure greater success with her offspring.