So I was able to recreate the issue by restarting the services. Once I restarted them, the Shibboleth iDP no longer responded.
Version 2.4.0 from CentOS 6 repository.
Installed on CentOS 6.5
Ok, so it's fixed now by stopping Tomcat. Waiting for that, starting it, and then starting HTTPD. After that, all was right with the world again. Very odd. Going to dig around in logs and see what I can find and see if I can break it again. FOR SCIENCE