Lung nodules 7 mm are they a concern?

It depends. Not all lung nodules are alike. The odds that a nodule is cancer depends in the appearance and size of the nodule, the medical history of the patient, the smoking history of the patient, and how the nodule changes over time. Radiologists, pulmonary physicians and thoracic surgeons are best qualified to determine the risk that a particular nodule is cancer.
Not always. These need to be followed with ct scans until stability (no growth) is confirmed. A prior diagnosis of cancer or occupational exposure is important.