Dan Driscoll used to be a smoker. During a regular doctor’s visit, his primary-care physician suggested that Driscoll be tested to see if he was at risk for an abdominal aortic aneurysm, a life-threatening condition that can be linked to smoking. The doctor said Medicare would cover the procedure. So Driscoll, 68, who lives in Silver Spring, had the test done and was surprised when he got a bill from Medicare for $214.