Though I am always ready to defer to our esteemed experts, I thought that I would give you a quick reply. The ridge is likely an indication that your pads do not cover the rotor all the way to the outside edge. This in itself is not a problem. It is an indication that your rotor is wearing. The rotor will have a minimum thickness stamped on it somewhere. You measure the rotor at several points and compare the value to the minimum. If you are under, then it is replacement time. A thin rotor will get hotter and cause brake fade and quicker pad wear. As some have said on the list, don't have the rotors turned - replace them. If it stops well now, and the rotors are thick enough, drive it and get ready to replace the rotors sometime in the future. They are cheap and must be replaced fairly often. Sometimes, a rock or other debris will become embedded in the pad and will cut a groove in the rotor. Small gouges are OK, but large cuts will eventually ruin the rotor.