New truck sound

Hey everyone...new to this forum. I just bought a 2015 v-6 tacoma after owning two tundras..decided to downsize. Anyway, I notice a strange noise when it is started cold..not the valve noise I've read about. When I turn it off, I hear something that sounds like it's (winding down)? after the engine stops...it does not happen often. Any ideas? Didn't hear it when I drove it twice at the dealership a couple of days ago. Bringing it to the dealer tomorrow...other than this , liking the truck.....thanks

 

Normal. Many threads on this. Two last week alone. Welcome and enjoy the new truck!

 

Just read on here where it is the smog/air pump ....same sound described...normal