Can somebody please explain this to me? It's like this in every set. I've looked for answers about this for a long time. I can't find an answer. Some bags have the white stripe with the number in black. Some have no stripe with the black number and white outline around the number. Only the number 15 bag has no stripe and no outline. I've seen it in dozens of sets and it's always this way. Someone has to know why this one bag is always different.