As I understand it JJ fixed the pin problem a while back....however there are still some of the bad pin tubes out there on the market , it isn't like they recalled all the tubes in the bad run/runs and some are most likely still kicking around in stock batches.
Tube retainers of some sort are always a good idea for hanging tubes that could potentially fall out. sockets don't often get retensioned as a routine and even those sockets that are good can loose their grip on tubes in some situations. someone mentioned a tube or tubes falling out during routine transport of an amp not long ago.
That being said those JJs had undersized tube pins which was the problem and the subsequent runs since they discovered that appear to have used properly sized pins , so it's a crap shoot if you can't check them but probably ok from a reputable seller.
Sure would be nice if someone designed a better retainer for some of those hanging tube situations that could be put in place without damaging a vintage amp.......