I'm pretty sure this is a manufacturing defect. It happened to my camera and Fujifilm's service center in Singapore replaced it without charge, within a day. When I went to pick up the camera, there was another gentleman there who had the same issue and he had his replaced by a service center in Japan while he was traveling there.
A part like this which is not supposed to be removable, shouldn't come off so easily so often. My cameras are used for work so they do take a bit of a beating, but I expect a 'pro' camera to be somewhat durable. Hence my thinking that this is a manufacturing defect and should be on Fuji to replace. Happy they did so in my case!