Originally Posted by THE TECH
None of that explains why the plug would strip coming OUT. Going IN, definitely possible.
I think he meant the hex pattern where the tool goes in is stripped, not the actual threads. That's my guess. If its the actual threads that are stripped, then this damage probably occurred during the last service when the plug was being reinstalled.
A fastener can strip on its way out if it was put in incorrectly, or if there was a significant amount of debris on the threads.