I was taking a photos with my new SB-700. The wide angle panel was in use while I was doing this. The session was something like arranging the stuff to be photografed, taking a few pictures, replacing the stuff with other items and so on. Suddenly the flash sounded different. When I looked the front lens of the SB-700 is smoked on the insided. It does however still work. I thought that I was safe since I didn't do any high frequency shooting and the overheating protection is in place. Did I miss anything or is this just bad luck?