[911monty]

Well Crap.... My first recommendation is a new plug, the old one may be in the process of rounding off internally, could make removal in the future questionable. But to see if I can help, I think you have a 2 piece hex bit and the machined hex has pulled out of the socket. This happened because while removing/tightening the plug, the hex started rotating and now has a friction bite on the plug. First try torqueing the plug correctly, then gently attempt to loosen the plug. Hopefully you will break the friction bite before the plug breaks free. Good Luck.