That's how mine began, and that's what I originally said, "it's not so bad", it only happens when it's cold, only in the morning. Now the sucker rattles like a 15 year old clunker, any time of the day, warmed up or cold, I'm embarrassed to be driving this thing now. Gotta call the stealership tomorrow.

 

The dealer fixed it, thank you all.

 

I need to take mine in as well.... I have 1800 miles and its getting worse, and now rattles every morning!! YAY!!

 

I have been experiencing the exact same issue at idle. I have also noticed that before the car warms the muffle makes the same rattle between 2800-3300 RPM. After it warms up its fine. I have been putting off going to the dealership with this problem because I wan tot put an after market exhaust on the car anyway.
Has anyone had this issue in the past and can confirm the issue went away after replacing the exhaust with an after cat back exhaust system? I am trying to eliminate the possibility that one of the many heat shields under the car are not causing the rattle. Or possible the factory Catalytic converters are causing the rattle.
I guess a better question to ask is, does anyone still have this same rattle with a cat back exhaust installed?

 

The problem is only in the muffler itself.

Supposedly ther eis an updated muffler than now fixes the problem all together. Infiniti Consumer Affairs told me this yesterday. They are going to expedite an updated muffler to my dealership for me soon.

But yeah if you replace with an aftermarket exhaust, the rattle will not be present.

 

NICE!

 

Had mine replaced and so far so good.

 

ahhhh mine is rattling again after i got it replaced

 

thats when it matters to me most.. i'll be hanging out with my friends and they'd give me a thousand praises on how nice the car is.. then i'd hope in, and as i drive off all they hear is a tin can grinding sound like my car has teeth and is chewing itself apart. its embarrassing!