No, Casino Rattle is not a song title although it would make quite a good one....i'll work on it!
I was playing my Epiphone Casino earlier tonight (have to give the Strat a rest now and again) and after a while there seemed to be a distinct vibration/ tremble that could be felt when bottom E, A and D strings in particular were struck. I check all the usual rattle spots like pickguard, p/u selector, etc and all seemed ok. All pickup combinations work ok too. Then I tipped the guitar over on its back and then back again and something inside seemed to slap against the back of the neck pickup as though it had partly come away. Also, when hit the strings with the palm of my hand there was a definite "slap" sound from that area. Obviously I'm going to have to get my local guitar techie to take a look but any ideas what it might be?