It seems that vBulletin doesn't test on PHP 5.4 or 5.5 these days. Either that or they're happy to just suppress errors rather than actually fix them.
I upgraded my forum today to vBulletin 4.2.2 and noticed these errors on a search page:
Warning: Declaration of vBForum_Item_SocialGroupMessage::getLoadQuery() should be compatible with vB_Model::getLoadQuery($required_query = ”, $force_rebuild = false) in …./packages/vbforum/item/socialgroupmessage.php on line 261
Warning: Declaration of vBForum_Item_SocialGroupDiscussion::getLoadQuery() should be compatible with vB_Model::getLoadQuery($required_query = ”, $force_rebuild = false) in …./packages/vbforum/item/socialgroupdiscussion.php on line 337
Luckily a user on vbulletin.com support forum has a fix: http://www.vbulletin.com/forum/forum/vbulletin-4/vbulletin-4-questions-problems-and-troubleshooting/4000233-warning-declaration-of-vbforum_item_socialgroupmessage?p=4000793#post4000793
What annoys me is that vBulletin released this version a while ago, but are still distributing it with this code error.