"I find that they do. Is that my imagination?"
Inhaling vapors or smoke of any substance can cause irritation of the airways and lead to coughing, a natural reflex designed to clear the large airways of foreign material and secretions. Habitually smoking large quantities of cannabis over a long time period can cause bronchitis and irritation of the airways, with increased phlegm and sputum as well as a chronic cough. For some people, the coughing induced by cannabis works well to expectorate secretions, and seems to help them breath better. Certain strains (and growing conditions) of cannabis seem to induce more coughing. Some connoisseurs of cannabis will be able to determine if the strain was grown indoors or outdoors, and whether of not chemicals were used(and how well they were flushed) based on the amount of coughing induced. If a certain strain of cannabis seems to induce more coughing (and this coughing is not desired), it may be wise to switch strains. Each strain is different based on genetics, growing conditions and the way it is ingested. If you experience a cough for more than a few weeks, I would recommend visiting a helathcare provider to have this complaint addressed.
andrewvanmd