This blood is surely not a sign of lung cancer, given your age, your trivial smoking history and the normal chest x-ray and CT scan. Blood in one's phlegm should never be ignored but you should not need any further testing beyond the imaging you have already had.
http://healthquestions.medhelp.org/blood-in-mucus-lung-cancer
Although the cancers that they are talking about are lymphomas (malignancy of white blood cells and lymphnodes) rather than a primary lung cancer. I hope the lesion is anything but cancer, but if it is, it's still small and can be acted upon accordingly.
http://healthquestions.medhelp.org/blood-in-mucus-lung-cancer
It is just as likely to have originated in your nose, throat or sinuses. Read More. The blood can come from the nose, mouth, throat, the airway passages leading to the lungs, or the lungs...........................
http://healthquestions.medhelp.org/blood-in-mucus-lung-cancer
Postural drainage and chest percussion are often used together to help loosen and remove mucus from the lungs. These airway clearance techniques help people who have a spinal cord injury, cystic fibrosis, or another condition that makes it hard for mucus to drain from the lungs. When mucus collects in your lungs, it increases your risk for lung infections. Postural drainage uses gravity to help drain mucus into the mouth by placing the body in specific positions. Each position drains different areas (lobes) of the lung. The mucus can then be spit or coughed out. Chest percussion (chest physiotherapy) uses clapping of the chest with a cupped hand to vibrate the airways in the lungs. This vibration moves the mucus from smaller airways into larger ones where it can be coughed up.
http://www.webmd.com/lung/tc/clearing-extra-mucus-from-the-lungs-topic-overview
One of the most common symptoms of pneumonia is a cough that produces mucus, which may be green or yellow or contain blood. Fever, chills, trouble breathing, painful breathing, headaches, confusion and fatigue are other warning signs.
http://www.livestrong.com/article/195795-what-are-the-causes-of-mucus-in-the-lungs/
However, if the body produces too much mucus and it begins to accumulate in the lungs, symptoms can occur. This includes coughing, trouble breathing, fatigue and chest pain or discomfort. In some cases, mucus is an early warning sign of a serious underlying disease.
http://www.livestrong.com/article/195795-what-are-the-causes-of-mucus-in-the-lungs/
Knowing the early warning signs of lung disease can help you receive treatment before the disease becomes serious or even life threatening. If you experience any of the following warning signs, make an appointment with your healthcare provider as soon as possible. Early detection could save your life.
http://www.lung.org/lung-health-and-diseases/warning-signs-of-lung-disease/
Coughing up blood: If you are coughing up blood, it may be coming from your lungs or upper respiratory tract. Wherever it's coming from, it signals a health problem. Chronic chest pain: Unexplained chest pain that lasts for a month or more—especially if it gets worse when you breathe in or cough—also is a warning sign.
http://www.lung.org/lung-health-and-diseases/warning-signs-of-lung-disease/
In patients with a history of smoking or who are otherwise at risk for lung disease, however, hemoptysis is often a sign of serious illness, including cancer. Read More. These symptoms strongly suggest that you may be having acute sore throat infection. In such cases tiny tinge of blood in sputum is common.
http://healthquestions.medhelp.org/blood-in-mucus-lung-cancer
Warning Signs of Lung Disease. A nagging cough or slight wheeze may barely register in the course of our busy days, but it's critically important to pay attention to even mild symptoms. Sometimes people think having trouble breathing is just something that comes with getting older. It is important to pay attention to these symptoms as they could be the first signs of lung disease, including COPD, asthma and lung cancer.
http://www.lung.org/lung-health-and-diseases/warning-signs-of-lung-disease/
is having mucus coming from the lungs a sign of cancer
No, having mucus coming from the lungs is not a sign of cancer.