it may be completely normal, but if your car never did this before, do one quick check. if one of your electric cooling fans goes bad, the remaining one will have to work overtime, i.e. after the car shuts down. to check your fans, start the engine and turn on the a/c full cold. pop the hood and look at both fans, with the a/c on both should be running, if one is out, there is a problem. the first one to go is usually the flat one on the left. if either one is off, turn off the engine and jumper the fan to see if its bad. if you dont have a/c you can just jumper each fan to check the motors and rule that out. hope this helps.