I just replaced rear rotors and pads. The outer pad clips walked out of seating on the caliper after driving a few miles (see pic). Any idea what went wrong? Autozone premium ceramic pads. Any tips appreciated.

 

I've never seen this happen. My guess is that they were not fully/properly secured during install. Try to get a warranty replacement from the same store and try again.
You notice the two metal bumps on the back. Those MUST be indexed to the holes in the caliper. I suppose it's easy to miss that. The pads will stay "connected" to the caliper just with the spring clips. You can turn caliper upside down and they will not fall out. But that is not sufficient during actual use.

 

You are correct, the buttons should be indexed into inside of caliper. I did not make sure of this when reassembling. I fixed it and so far so good. Thanks for your input, I appreciate it.