Hi,
I have had the same thing happen to my unit yesterday. I bought it on release so found it a bit quick, contacted support and they reffered to the warranty and that I could send it back for a replacement unit. Hope this is not a problem that all the units have, i am very happy with the headphone so far, and the headphone can work perfectly fine with lose earcup.
I would say that i expected Nothing to stress test these swifle mechanisms to oblivion… but apperently not good enough.