Squeak when hitting Bumps

I have a new 2005 Xterra S that I've put about 6,000 miles on since I purchased it. When I hit bumps, There is a squeak sound that sounds to come from underneath the C, but the dealer says it a bushing in the fuel tank that needs replacing. They've never actually looked at this bushing, but say that similar problems have been reported and the bushing replacement was the solution. Any feedback on this one b/c I'm skeptical about the solution to this problem.