Add note about serializing objects.

queues.md

@@ -127,6 +127,8 @@ You may also push a Closure onto the queue. This is very convenient for quick, s
 		$job->delete();
 	});
 
+> **Note:** Instead of making objects available to queued Closures via the `use` directive, consider passing primary keys and re-pulling the associated models from within your queue job. This often avoids unexpected serialization behavior.
+
 When using Iron.io [push queues](#push-queues), you should take extra precaution queueing Closures. The end-point that receives your queue messages should check for a token to verify that the request is actually from Iron.io. For example, your push queue end-point should be something like: `https://yourapp.com/queue/receive?token=SecretToken`. You may then check the value of the secret token in your application before marshalling the queue request.
 
 <a name="running-the-queue-listener"></a>