Yeah, tubular tire repair is tedious and I do all of it in the winter when I'm less busy riding. If your Sprinter was already worn it's probably not worth the effort. If you didn't find the cause of the flat, it may just be the tube inside failing at the valve stem, which usually happens to Contis when they get old. My guess, it was just a random incident, and you will probably not have another front flat for years. One thing I do after avery ride is quickly check my tires to see if there is any glass or other sharp items embedded in the tire tread that could eventually work itself into the tire and cause a flat.