I get bright red blood in my stools quite frequently. With IBS I often have periods where I am constipated for days at a time. If I strain to relieve myself during these times, I can get a small tear, and subsequently blood.
My doctor always told me that bright red blood is rarely a worrying sign. It hasn't been inside of you long enough to have become the black, sticky stuff that you really have to be worried about. If it's bright red, chances are it's from the area around the anus itself - hemorrhoids or a fissure, most likely.