It probably means that a trigger happy customer tried to open a refund request for Item Not Received before the outer limit of the delivery deadline and the system wouldn't let them do it.  Ebay counts this as "protecting your reputation", just as the automatic five stars for postage cost for Free Postage listings counts as "protecting you reputation".  The item in question probably turned up the next day and the buyer was happy. It's all just Ebay spin.