No, his CO2 levels are up due to poor lung function, most likely. But it could be metabolic or pharma drug related. He is not blowing off his CO2 properly and this will create an acidic ph in the body.
Does he have some kind of respiratory disease like COPD in the making?
In fact, just that they know his CO2 levels are up means that they checked his elcetrolyte panel which indicates to me that they are pretty concerned about something. This site may be informative to you.
Carbon dioxide is a normal metabolic waste product. The lungs eliminate it. There could be more complex things going on also