Delayed lung sounds?

Hi all! I work in Oncology and have an 'out of curiousity' question.. I was auscultating a man's lungs the other day, one lung sounded normal... but the other seemed to have a delay between the time that I saw his chest rise and actually heard the lung sound begin. Hope this makes sense? I could see that he'd begun a breath visually, but it took a portion of a second to actually hear it through my stethoscope..

Then I would be able to hear it it last a fraction of a second after the chest had ceased movement.

Just trying to figure out what in the world this is for curiousity sake. I looked online, and saw mentions of delayed lung sounds, but couldn't find an answer. Thanks!!