I recently went through a bout of colon cancer. I will share with you some of the things I learned.
Plan on seeing the doctor as previously suggested to be safe. The color of the blood can be an indicator. If the blood is bright red, it is most likely hemorroids. If it is darker in color, it may be an indicator that there is bleeding somewhere along the colon. It is not necessarily an indicator of cancer. If a member of your husband's family has or had colon cancer, have your husband mention this to his doctor if he hasn't already. Colon cancer can be hereditary. If he started bleeding recently, it is most likely a recent event of hemorroids or bleeding. Don't mess around with it. Have your husband suck it up and go see his doc. Best of luck
Do you know if he has hemorroids, fissures? Does this occur on a daily basis? I would suggest going to the doctor.