Very strange error message

Hello list, Today I am facing a rather strange PHP error message on a production system using PHP 5.4.41 with APC: [09-Jul-2015 15:06:43 Europe/Brussels] PHP Fatal error: Access to undeclared static property: Stash\Item::$/opt/app/a373/apache-pro/htdocs/vendor/tedivm/stash/src/Stash/Interfaces/ItemInterface.php in /opt/app/a373/apache-pro/htdocs/vendor/tedivm/stash/src/Stash/Item.php on line 348 That line 348 is this one: https://github.com/tedious/Stash/blob/master/src/Stash/Item.php#L348 and contains: $cacheTime = self::$cacheTime; $cacheTime being defined in the class as: public static $cacheTime = 432000; // five days (see: https://github.com/tedious/Stash/blob/master/src/Stash/Item.php#L59) A message like: "Fatal error: Access to undeclared static property: Stash\Item::$cacheTime" is virtually possible, but: "Fatal error: Access to undeclared static property: Stash\Item::$/opt/app/a373/apache-pro/htdocs/vendor/tedivm/stash/src/Stash/Interfaces/ItemInterface.php" ? How is it possible that the filename of the file containing the interface being used by that class appears instead of the variable? Any clue of what happened? PHP bug, APC one? Memory corruption? Bad karma or planets wrongly aligned? Cheers, Patrick