I just got as flat from a stable this weekend too! Actually first, I managed to pull the valve out of the tire (before the start of a tour/ride). That was my first ever tire change. All went well, slow, but well. The next morning, the same tire is flat. I pull it apart and find a pin hole. So now I patch it and again the next morning, it is flat! I either missed another hole or did a bad job with the patch. I'm gonna try again in the morning, then I will keep that tube for a spare. At least now I am not afraid of having to change a flat on my own!