What would cause random mild chest pain (center)when breathing in deeply that continues for about an hour and then randomly stops? not exercising, not in cold weather, no viral infections. just comes out of no where and stops?

It is likely to be musculoskeletal chest discomfort from the deep breathing. The chest wall has muscles, cartilage, bone and any of these structures can be stretched and/or inflamed and then cause the symptoms you describe. Deep breathing may be stretching a muscle, for example, and lead to this discomfort. You can take acetaminophen or ibuprofen for symptomatic relief. See your doctor if worsens.