Interesting.....
I just happen to have a Whirlpool Dryer (Model WED5810SW0) that just started running really HOT....even on lower temperature settings. I haven't had a chance to do any troubleshooting yet, but I hope to tomorrow. I'll first check the venting for a blockage as suggested above, but I think something else is going on.....after the dryer has been turned off, I could still hear a faint 'buzzing', so I unplugged it from the wall. The Timer was replaced a couple of years ago with a 'refurbished' one. I wonder if that has an issue too....?