I have an '06 RL with 105K miles and have recently noticed a noise coming from what appears to be the driver's side rear area when I run over anything that could produce a small bump. It sounds like a loose suspension component; kinda makes a rattling sound. The truck rides normally, doesn't list to one side, and when I push down on the rear as if doing a 'shock bounce' test, it reacts perfectly. Any ideas? Anyone else had a similar issue?