[ceejay]

I was having the same problem. I called Home Warranty and they told me I had to clean the vent...I reminded them that it was up on the roof and they told me to hire someone to clean it!

When we sent our lawn guy up there, he found that the vent was screened instead of having the flaps, so all the lint was trapped...a definite fire hazard!

I wouldn't be surprised if that's what your problem is...check it in a hurry!