Because of lighting your scan makes the groove appear to be a very deep "V". Is that the way it really is, or is the shape more of a shallow indentation around the edge of the chip and that the shadows are obscurring this in the scan you made?

If shallow, that is not un-natural for an old (30 plus years) clay composition chip. In fact, that condition can be the basis to verify that a chip in new condition, is an old chip and not a newer made chip.

However, if that is a deep "V" in the chips. Then that is not a normal condition.

Jim (Gaming Ore) Follis