Dryer lint burns well and is a leading cause of houshold fires. And even with cleaning the filter after every load lint still is trapped in the hose and vent to the outside. You should check the vent and under the outside cover 2-3 times a year and check and clean or change the hose as well.

A shop vac works well for getting into the hose. Your dryer will be safer, and more efficent as a bonus.