Question about YS640

Did the initial burn in twice, once with regular grates and again with direct grates. Everything went well. For my first cook I did chicken at 290 deg. Cook went well. When I shut down (turned switch to off position) the fan and everything went off about 5 to 10 seconds. I was worried that it was not getting the proper cool down so I switched the power back on and let the fan run the correct correct amount of time. It is probably something I did wrong. I may not have unplugged the unit after the last burn it. Could that have been my mistake? Used the grill again for a salmon cook and everything went as it was suppose to from cook to shut down. Thank you for any input.