This is very common and does happen because of age. Your oil pan is aluminum ( a soft metal ) and since that drain plug (the bolt) has been replaced and re-installed so many times, eventually it will start to ruin the threads on the aluminum pan.
This is not the shops fault what so ever, they just removed the bolt and found out that all the threads were gone.
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Wednesday, September 2nd, 2009 AT 8:59 PM