“A dryer and the attached vent system requires regular cleaning and maintenance, just like your furnace or other fuel burning equipment. Lack of regular cleaning and maintenance of dryers and their attached venting systems, has been identified as causing fires.”
The BC Safety Authority has issued a safety alert about maintaining your dryer vent. The upshot is that when lint collects in the vent, the dryer has to work harder to push the air out. This will heat up the dryer even more, creating a feedback loop and possibly a fire hazard. Read the whole alert here.