Same here.
It was an old plug I had got on ebay years ago.
It worked fine for many years with every iphone besides doing that weird glitch with the iphone 5.
Good to know its not the phone.
Since I only picked my iFone 5s in March this year, I wasn't aware that there might be any bogus plugs supplied in new, OEM fone packaging. How can I tell if I might have one of those bogus blocks?