You can ignore it. Nothing bad will happen.
You should, however, consider upgrading PHP to 5.5 (or 5.6) which comes with Opcache bundled in. I don't want to overstate the benefit but you typically see the load come down a bit on the server which is no bad thing.
Also, you should note that PHP 5.4 ceases to be supported in September (http://php.net/supported-versions.php)
PS. Better not to raise threads from the grave. It would have been better to create a new one.