why dose my radio stay on after i turn the truck off and open the door? on 2002 Ford Excursion

sometimes i can turn my truck off but the radio continues to play,Even when i open the door,Then it don't come on when i start the truck,this has happen maybe two to three times a mouth.

Asked by for the 2002 Ford Excursion
Sounds like the relay that handles the delayed shut off of the radio (accessory delay relay - in the central junction box) may be sticking on intermittently.