Good eye! Yes, it is. When I came back from Vietnam in '66, I left the knife in its sheath, stored with my uniforms in a box on the basement floor. Dampness from humidity and some flooding ruined the sheath over the next few years. At some point in the 70's I threw out my moldy uniforms and the sheath, and got a waxed replacement, to resist dampness. On one of my visits to the Randall Shop Pete polished out a couple of small spots on the blade, and warned me never again to store it in its sheath, even though stainless. In the decades since, it hasn't been in the sheath at all!