In this image from the same night, it can be seen throughout the image.
http://s611.photobucket.com/albums/t...nt=canopus.jpg
Ok it probably isn't focuser tilt. I checked my old photos and it's still there; this leads me to believe the mirror may actually be pinched too tight; either by the mirror clips; or by the collimation push/pull screws.
I guess I could start by adjusting the push/pull screws.. loosening them up and imaging at same time to see what affect it has.
Then if nothing changes; pull the mirror out, and loosen the mirror clips. Guess I should give the mirror a quick bath at the same time.