I Occasionally Have Blood (bright Red) When Defecating. I Also,

I occasionally have blood (bright red) when defecating. I also, though less frequently, have a "phlegm/mucus", of a dark red color, mixed with it. It generally happens while straining to defecate. It feels like a stool is coming out but turns out it's only blood. I have had one colonoscopy about 5 yrs ago. Overall it was fine though a few small polyps were removed. Six months ago I went to the proctologist for an office exam and she said that I did not have hemorrhoids. She wants to schedule me for another colonoscopy, and I will, but should this concern me?