I purchased an apparently genuine early 2000s Stingray 4 string with as hipshop DTuner from a private party and have used it with great satisfaction for several years. While cleaning it recently I noted what appears to be a vertical ridge in the finish on the back from the bottom of the bass (when held upright) just inboard of the battery access all the way up to the cut-out. Nothing like it appears on the front. Is this an indication of a seam in the body? I thought all the Stingrays were solid slab bodies. Did I get taken?