You probably do not need to be concerned, but the degree of suspicion would be based on a number of variables including but not limited to, your age,
smokingQuitting smoking
Smoking - tips on how to quit
Smoking and copd (chronic obstructive pulmonary disorder)
Smoking and smokeless tobacco
Smoking hazards history, geographical location,
occupationalOccupational asthma exposures, the shape and margins of the nodule. 6mm is considered a small nodule and the majority of nodules this size are
benignBenign ear cyst or tumor
Benign positional vertigo. Serial x-rays to observe for change in size, over time, would be a reasonable approach. You should also try to recover any and every previous
chestAcne, cystic on the chest
Adenocarcinoma - chest x-ray
Aortic rupture, chest x-ray
Aspergillosis - chest x-ray
Bronchial cancer - chest x-ray
Chest mri
Chest pain
Chest stretch
Chest tomogram
Chest tube insertion
Chest tube insertion - series x-ray ever taken. One of them might reveal the presence of this nodule, in retrospect and, if so, the question of concern would be moot.