Main Stock Muffler Rattle
 

Hey all! First, I apologize if this is supposed to go in the Intake/Exhaust sub forum, but most of what I saw there was aftermarket-related posts. I'm having an issue with my stock muffler where it's making an annoying rattling sound, usually when the car is in gear. It comes and goes, regardless of engine temperature. It usually gets worse when the AC is on and almost always goes away when I put it in neutral.

I took a look under the car thinking the muffler might be hitting the heat shield, but from what I can see/feel, it's not (unless the two parts get very close towards the top, which I couldn't reach with my hand).

A friend jokingly mentioned that maybe someone threw a screw or rock in there.. So I'm guessing it's that, or it's touching the top of the heat shield, or something came apart inside the muffler and I need it replaced. Here's a clip: https://vine.co/v/Mlhv0wE7xEe

Anyone have any ideas? I'm past the factory warranty. Before I take it in for an extended warranty claim and put down the deductible, I was hoping to get a consensus from the Z community to see if it's worth taking apart further.

Edit: Not sure if this matters, but it's a 7AT

The internal muffler design is pretty intricate. Perhaps a weld broke or something.

Yeah, I'll probably just take it in. I'm tempted to disconnect it and take a better look, but the dealer will probably give me **** for not replacing the gaskets when I reattach it. I'd rather not risk them denying the claim.