Said notice only applied last week after a bomb scare, afterwards some locals decided to burn out a signalling room, as a result the signalling system was not at full capacity resulting in some delays
The 20:45 Dublin Belfast had a bus substitution from Newry onwards that week as well while work was undertaken to repair
More details
http://forum.platform11.org/showthread.php?t=2290
Iarnrod Eireann never issued a notice concerning the bus transfer