Weird Sound when truck is turned off

A couple times a day when my truck isn't running it makes a very strange noise for about 10 minutes, usually near the rear of the truck I usually only notice it when I'm sleeping in my truck and it wakes me up, which occurs almost every night I sleep in it. The other day I caught it in its act during the day and was able to capture it. The YouTube video is where it transitions from loud annoying noise to soft annoying noise. Happens randomly and always when turned off, sometime hours after the truck was last running. Anyone know what the hell this randomly occurring and annoying noise is?

https://youtu.be/N0-9bxajjzs

 

Am I supposed to be hearing something in this video?

 

Yes, might need to turn the volume up higher. Noise is most pronounced in the beginning of the video.

 

Fuel evap leak check. Normal.

 

Normal, most cars do it.

 

Thanks!

 

If you read the Owners Manual it explains that it will do that approximately 5 hours after you turn the truck off.