Vertically facing dispenser/dropper top texture slightly inconsistent with its other textures

The usual texture is pretty smooth and dull looking, but the dispenser/dropper hole textures use a slightly shinier looking cobblestone.

Where the texture this was derived from came from is unknown - it certaintly didn't seem to appear in any released Texture Update resource pack, and it only partially matches up with the flatter cobblestone texture surrounding it in the images.