Fell on my back , had cat scan , revealed (2 ) 4mm lung nodule pulmonary doctor says i should have nothing to worry about, follow cat scan in 6 mnth?

Agree: Lung nodules that small, in someone your age are probably nothing to worry about. I agree that a follow up scan is necessary to ensure that they do not enlarge.

Probably overkill: For nonsmokers, with nodules in that size range, we recommend no further follow-up. If you are smoker, stop smoking. If any follow-up is necessary, 12 months is probably all you need.