It could be that (a) the box is made in one place and the bag another, (b) the box and the bag aren't a match (this is frequently the case at department stores and even Chanel boutiques give the wrong box that doesn't match the bag upon occasion), or (c) there was a mistake about the sticker (I find this the least likely scenario). In any case, it really doesn't matter about the box; for classic flap bags, you don't get a box with the sticker anymore, so there is no worry about where the box is made.
I think I have received the wrong box for jewelry/belts/bags about as often as I have received the correct box. Usually, they just grab the first box they see, which doesn't match the item. I don't find this to be a big deal, as again, I carry the item, not the box.