Based on reports from others I've seen, it's fairly common. Now if it is really loose, take it back to get a replacement. I myself can make that same noise with my APP if I move the top of the case quickly.. but it isn't something I care about. The hinge is no where near as tight as the very first Air Pods.. even Air Pods 2 it was looser.. They changed the material in the hinge for 2 and Pro.... cheaper materials.