A 45-year-old male presents with chronic irritative dry cough, fatigue, and progressive dyspnea worsening with exertion for over 5 years. Physical examination: normal temperature, pulse 102/min, respiratory rate 30/min, mild cyanosis. Chest X-ray shows bilateral diffuse reticulonodular opacities, most prominent in the middle and lower lung fields laterally, with ill-defined borders and honeycombing lucencies. The most likely physical examination finding is: