I have an 05 and after I back up, put in drive and go about 20 feet I hear what sounds like a spring releasing. Has anyone else noticed this?

My 2000 XTerra daes not do that, but My 2004 Tundra 4.7L DC, did that. I took it back to dealer after they take a look at it they told me it was an ABS Actuator sound and told me not to worry about it. But in your case could be something else.

Thats the nice thing about having a newer truck.. just take it to the dealership and let them figure it out. :D

Then post up here whatever they find. ;)