syslog udp listener died

I'm getting the following error repeating every 5 seconds when I start logstash:

WARN – : syslog udp listener died {"address":"logstash01:514","exception":"bind: name or service not known","backtrace":["org/jruby/ext/socket/RubyUDPSocket.java:144:in `bind'","file:/usr/local/logstash/logstash-1.1.0-nagios.jar!/logstash/inputs/syslog.rb:115:in `udp_listener'","file:/usr/local/logstash/logstash-1.1.0-nagios.jar!/logstash/inputs/syslog.rb:78:in `run'"]}

This happens regardless of the config I am using.