Haunted Fuel Pump?

Here's a weird one !
Truck ('09 V6 4wd stick) was parked outside (cold) for about 5 hours,
As I walked by to get firewood, noticed that it was making a whirring sound - probably fuel pump.
Stopped by itself after a couple of minutes.
Anyone know of some timer in these trucks that would do this?
maybe an emissions related doo dad?
Thanks,
Jim

 

Makes sense, I was about to start an exorcism .......
Christine!

 

If you look in your Owners Manual it says that your fuel pump will automatically turn on for maintence for about 5 minutes.. Its just to get fuel in the fuel lines and get it ready for the next crank