The bellows are flexible. That's good for movements, but it means that the folds can become inverted fairly easily, and if the front standard isn't move all the way back to the rear standard, the bellows will tend to deform. If one closes the camera with the bellows like that, then they will get creased. As Merg says, it's likely just cosmetic, but as many have said, all it takes is a second or two to make sure everything is where it should be for closure, and there's no inverted pleats.