[gregbradley]

It looks natural to me. These widefield lenses usually have some aberrations/distortions. It looks like he may have some slight tilt where the left side has been affected and the right has not.

Possibly the stitching process may have elongated some as well. Looking at it again I'd say its a stitching thing as the stars are tight to the left of it and to the right of the elongated stars.

I'd say being a Canon he may have used a Canon widefield lens which probably does not do well off axis.

Suspicious aren't you? hehehehe
Greg.