my apologies everyone - it was working rock solid for a few days and I got lulled into a false sense of security and took my eye off the site for a few hours :/ I am still working on some alerting to tell me when rabbitmq dies, but it's obviously got some room for improvement.
In any event, I am aware, I've fixed the current problem and the queues are draining now. I'll work on a better monitoring and response automation system tomorrow.