I have a '15 Ultra Limited with 9,000 miles; buddy has a '15 SGS with 11,000 miles. We both found the front spark plug wire wearing at the point where it contacts the fuel tank near the front cylinder. The routing needs to be corrected. Suggest you check yours before it becomes an issue. Easy fix.
Mine too and I installed a felt sticky pad on the "tunnel" section of the tank where it was rubbing. The pad is the kind you put on the bottom of a chair when you have hard wood floors.
A piece of small splitloom conduit around the plug wire after you bend it is a liitle more protection, especially if it has a rub make on it. I used the piece of conduit left from my finned head bridge kit.