Best to get checked. Bleeding per rectum may originate in the anal canal, the rectum, or further up the line. Frequent anal sources of bleeding include hemorrhoids & fissures, that may respond to modifying stool texture (fiber, softeners) and topical agents, or require further intervention. Similar bleeds can be seen with anal & rectal cancer, infections, ischemic colitis, diverticular bleeds, inflammatory bowel, etc.
Probably not serious. The most common reason to have intermittent rectal bleeding is hemorrhoids. Warning signs to get prompt evaluation include: large volume bleeding, associated abdominal pain, change in bowel habits, black tarry stools, weight loss, or bleeding persisting longer than 2 weeks. Symptoms of anemia associated with bleeding also require prompt attention, including fatigue, dizziness, or breathlessness.