If you use fabric softener (sheets or liquid) you must "wash" your filter screen. Yes "wash" it.
Fabric softener puts a coating on your clothes and the dryer screen as well. The coating prevents the air from flowing through the filter and taxes the entire drying system. So, take out the screen filter and see if it will hold water. If so, you really need to wash it with soap and water until the water flows right through. Doing this will lengthen the life of your dryer's heating element and motors.
Try to remember to do it often depending how much you use the dryer. I was told this by the dryer repairman after I paid him a boatload of money to replace the heating element in my dryer.
