Sweeet image! If One looks at the flight path approximately 45% (of the width of the picture) from the left (just after the path is coincident with the star trail) there are a couple of small blips slightly brighter than the path. Separation charges, maybe? Kind of a while after the apparent burnout of the major engines, but maybe?
One blip is a star trail right in the flight arc. There is a brightening in the first part of the launch--probably where the engines are throttled up after max-Q. The first stage path has a slightly greater bend after throttle up, but efficiency is close to maximum anyway. Delta and Atlas are the two sweetest big launchers on the planet.