24mmx19mm centrally calcified lung nodule should I be worried?

Yes if new. Some people contact TB as children and develop calcified nodes. If this is new and if you have been a long-term smoker do not fail to follow up with the doctor who discovered this because might be a malignancy. An old x-ray film could help to settle this matter.
Probably not. Most nodules are not cancer and centrally calcified nodules are universally recognized as benign. Not all calcification patterns re associated with benign conditions, so the pattern is important but centrally calcified is nearly synonymous with benign. .
Concern. Not fear most likely benign. But get and compare any old x-rays or ct scans. Regular ct followup, until certain no change. Then remain observant.