I would be very surprised if the dealer shoots you down (pun intended) on an issue like this following the purchase of DT11 (EELL?) that is still under warranty. May be that they send it back though, which could take a while. I'd hate to part ways with a gun for any length of time. If it were me, I'd certainly email Beretta customer service parallel to contacting the dealer. This being a flagship model, chances are Beretta themselves wouldn't want to risk dissatisfied customers.
That said I am very curious as to the cause. While its hard to tell from the images how much, the noise alone says way too much wiggle room there. Was it snug before and if so for how long before it started moving? Did it develop incrementally or all at once?