I am using a Nikon D90 and SB600 Speedlight. The speedlight has started giving three "mini-flashes" before firing the main flash. This delay is causing me problems (starting to take the camera down from my eye before the main flash goes off). Flash setting wrong? Camera setting wrong? What? I do not recall the flash ever doing this before. Very frustrating. Very difficult to get any "quick" flash photos. Any advice?