Took my 2011 RT to dealership over the same issue, they just smeared grease in the tract and said even if they replaced the motor or tract it would still do it. They put on the service ticket they found no issue with the seat. At least you guys got yours replaced. Mine still grinds today
On my 2012, the dealership ended up replacing 4 seat tracks, and two seat lower frames due to weird movement during the time I owned her. They also installed the new bolts for the seat per a TSB.
I had this problem day 1 with my 2012. literally when I picked up the car from the dealership, I noticed this right away.
You see I had to move my drivers seat forward to install one of my kids car seats, and this is when I noticed the klunk/grind with the drivers seat. I have two kids (twins), so I used my drivers seat (moving it forward and rear), whenever I had to get one of my toddlers into the car, so I feel I was just seeing and experiencing this issue more than some folks who might never really move their driver seat as frequently as I did.
When I was accelerating or braking hard enough, I felt the bottom of the drivers seat literally moving, and it was confirmed by the Service Manager at my service dealer that the lower seat frame was in fact moving/rocking back and forth, when it should not have been.
Before I traded in my 2012 for a 2014, the 2nd lower seat frame was installed, and the problem went away again.
My new 2014 does not have this issue so far.