Bada Bing

I have a 2021 S4 Premium with the stock (non-B&O) sound system. I get some buzzing/vibration from the rear parcel shelf when playing certain types of bass-heavy music even at moderate volumes. Even though there are two speaker grills, there is only 1 woofer installed on the driver’s side. Is this a common issue and can I do something easy about it? I haven’t cranked up the volume enough to damage the speaker, so I’m pretty sure it’s from the parcel shelf.