My Husband Is A 50 Year Old Smoker. Recently I've

My husband is a 50 year old smoker. Recently I've noticed his fingernails curling upwards at the tips and his fingers seem...different. It is hard to explain. He has not seen a doctor in more than 30 years and other than obviously needing to quit smoking, he is in good health. Do you think the change in his fingernails is due to age or something else?