Zend OPcache class loading error - symfony

Question

Every so often, one of the instances in our application will start throwing this error:
[Fri Aug 29 14:23:25.359848 2014] [:error] [pid 2759] [client 1.2.3.4:58627] PHP Fatal error: Zend OPcache class loading error, class FSC\\HateoasBundle\\Serializer\\EventSubscriber\\EmbedderEventSubscriber in /var/app/current/vendor/composer/ClassLoader.php on line 183
It happens when loading any page. I've tried composer dump-autoload, but that does nothing. Repeatedly restarting Apache is equally useless. This is PHP 5.5.7 running on Apache 2.4.6. Here's the opcache preferences:
[root#ip-1-2-3-4 html]# php -i | grep opc
/etc/php-5.5.d/opcache.ini,
opcache.blacklist_filename => /etc/php-5.5.d/opcache*.blacklist => /etc/php-5.5.d/opcache*.blacklist
opcache.consistency_checks => 0 => 0
opcache.dups_fix => Off => Off
opcache.enable => On => On
opcache.enable_cli => Off => Off
opcache.enable_file_override => Off => Off
opcache.error_log => no value => no value
opcache.fast_shutdown => 1 => 1
opcache.file_update_protection => 2 => 2
opcache.force_restart_timeout => 180 => 180
opcache.inherited_hack => On => On
opcache.interned_strings_buffer => 8 => 8
opcache.load_comments => 1 => 1
opcache.log_verbosity_level => 1 => 1
opcache.max_accelerated_files => 4000 => 4000
opcache.max_file_size => 0 => 0
opcache.max_wasted_percentage => 5 => 5
opcache.memory_consumption => 256 => 256
opcache.optimization_level => 0xFFFFFFFF => 0xFFFFFFFF
opcache.preferred_memory_model => no value => no value
opcache.protect_memory => 0 => 0
opcache.restrict_api => no value => no value
opcache.revalidate_freq => 2 => 2
opcache.revalidate_path => Off => Off
opcache.save_comments => 1 => 1
opcache.use_cwd => On => On
opcache.validate_timestamps => On => On
We're all at a loss as to what's going on. Anyone have any ideas?