There is no dedicated warning for authors available when the replication queues start to fill (not for pages nor for assets). But the replication queues offer MBean support so you can monitor the queue size.
There might a number of reasons why replication queues grow or only a single replication starts to grow and others not. And pointing authors to it might always make sense (imagine a case where you shut down a single publish for maintenance reasons and its queue start to grow; that's a controlled situation and the behaviour is expected.
Jörg