Trying to figure out what it was before taking it to the dealership to check it.

As I was driving the 2017 X1 x-drive on Eco Mode and decided to change to Comfort mode. After a block or so in the road as I was trying to go to the side road, slow down the suv . All of a sudden I felt like I ran over something like a brick (it was loud) in the back and the suv shook. I went back to the same location to see if there is anything on the road. There was nothing, no pothole or any objects. I checked the tires, there was no issues.

I have no idea what made that noise and afterwards it was driving fine. Does anyone experienced a same issue? What can I do to check it? Can this be a random road debris that went away or ice stuck somewhere?

Thanks,
breamerx1