How high was the field you were shooting?
This looks like prismatic atmospheric diffraction. That's in the sky, not in your scope.
Normally it's blue on the top and red on the bottom, but I don't know how your scope was oriented. The lower in the sky, the worse it is.
If the alignment of fringing is consistent all across the image, and if the orientation of the fringing is along the vertical direction (not north) from your location, then the problem is most likely atmospheric dispersion. What was the altitude of your object at the time the image was taken? Atmospheric dispersion becomes markedly worse as you decrease in altitude.
The object is M74 which I started shooting right at dusk when the object was at an altitude of 52 degrees. It was a pretty long run for about 5 hours total so it passed the meridian at an altitude of 72 degrees and when the imaging was done, it was back down to an altitude of 52 degrees.
It was a combination of RGB and Lum frames with the Lum frames taken at the beginning and end of imaging while G and B were taken close to the meridian and R taken slightly off from the meridian.
The orientation of the red is predominantly to the North to North-East in the image though although the fringing is consistent across all the stars in the image.
Does this still sound like atmospheric dispersion? If so, is there much that can be done to minimize it?