I had exposure delay on initially. This separates the imperceptible preflash from the flash. I must have had this on accidentally a few nights ago and thought it was a normal preflash. When it disappeared I thought I had a malfunction when in reality everything was working properly.
I don't think exposure delay is indicated anywhere in the EXIF data.
Last lesson learned;
TURN OFF EXPOSURE DELAY BEFORE TURNING OFF CAMERA.
"Cameras and lenses are simply tools to place our unique vision on film. Concentrate on equipment and you'll take technically good photographs. Concentrate on seeing the light's magic colors and your images will stir the soul." Jack Dykinga