I recently bought a new Norton 4k/8k and a naniwa 12k and noticed that they did not wear off evenly using the flattening stone. Is it expected to have to flatten norton stones after soaking them in water for the first time? They are honing much more predictably now that I have flattened them for the first time. It took a lot of flattening to wear off the pencil cross marks they recommended to use as indication of flatness. Took about 10 minutes of flattening to get it down to 'flat'.