[Joe_G.]

Not Unusual.

The printing paper (albumen) was/is very fragile and typically placed on a mount soon after developing the image. In the case of cabinets, the photo is almost always smaller than the standard cabinet mount on all sides. But on cards such as N172s and other smaller formats, the end product is typically one of many images in a matrix (24 card matrix on N172s) that were glued to a large mount or cardboard backing. This large matrix of images is then cut down to size to form individual cards. The cards that are on an outside border of the matrix can sometimes be found with the albumen paper falling short of the mount/cardboard backing.