Camera lens is loose in the body of the lens.

I just purchased the sony E 11mm f/1.8 from a reputable retailer, however they didnt have it in stock and offered a decent discount on the display case. I inspected it and looked great, however i've got it back home and i shook it for whatever reason and it is loose in the frame (like a marraca) is this normal and nothing to worry about or do i have to return it?