Although it is true that the method no longer exists, it's for that very reason I had the event listener set to be disabled when the add-on was exported:
Rich (BB code):
<listener event_id="front_controller_post_view" execute_order="10" callback_class="AddOn_Listener" callback_method="frontControllerPostView" active="0" hint="" description=""/>
I don't recall the same behaviour occurring before, so I believe this to be a bug introduced by the new Class helper introduced in XenForo 1.3.