I don't think that IS a dustbag, I think its either material that just wraps around the purse in the box (like a glasses cleaning cloth or something) or tissue paper - it doesn't seem thick enough to actually be a bag.
But still, they never use that for the smaller items that dosen't come with dustbags - they're just wrapped in white thin paper with tiny trees on. Should be a dead giveaway for a fake if this kind of wrap is shown, don't you think?