I gaurantee it. Get some one that says their truck is perfect, then get someone that has OCD, or is a quality inspector, and I gaurantee they'll find something wrong.
I have a similar sound, but mine sounds like a loose clip shifting when I come to a sudden stop, turn sharp etc.
I've learned long ago to not let interior noises/rattles irritate me. If you let them, the dealer will end up tearing apart the interior, and I gaurantee it'll never be the same. Noise may be gone but you're left with ill fitting panels, and scratches everywhere.
I wanted a low optioned LT Trail Boss, only has the safety package. They are hard to find without 5k-8k worth of options. I'm pleased with it, would have liked more off, but I got a good offer on my trade and it was one of only four LT Trail Bosses within 150 miles with an MSRP of under 51k.
Good luck with your search!