I had a tune up done on my 02 Buick Rendezvous in August 2011. I have not touched the spark plugs etc since and have maintained oil changes and fluids since. My car just broke down with a pop a engine and a flutter sound. The tow truck driver and an independent mechanic of 40 yrs, looked at it. A spark plug blew out; both looked at the spark plug and see slivers on the threads and said they are pretty confident it was partially stripped being put in and just eventually blew out under pressure. They dealership that the tune up was done at said it could be possible at the beginning but now that I'm not willing pay additional costs, are stating its not possible to have lasted a yr and three mont hs. Can apartially stripped spark plug hold out this long before blowing out?