Symfony2 Classloader warning

Question

This warning shows up half of the time when the pages in the project load. So this doesn't show up on every page load. I have tried updating composer, cleared cache,etc. I have no idea why this started a month ago. I use Symfony 2.3.18, PHP 5.3.3-7

Warning: Attempt to assign property of non-object in /www/current/vendor/composer/ClassLoader.php on line 195

http://i.stack.imgur.com/ItjbX.png

[EDIT]

I also would like to note that in production this Error/Warning doesn't show.

Answer 1

We restarted Apache/PHP to clear the APC cache.