Ct - moderate colonic stool burden. is this of concern?

Without more information it is difficult to give a complete explanation. However, "moderate colonic stool burden" just means you have poop in your colon. As to what specifically the radiologist means by "moderate" is unclear.

Not necessarily of concern, it suggests a degree of constipation. A balanced diet, proper hydration and physical exercise are the main ways of avoiding constipation in the long run.