That is the issue related to the update site. The 1.4.0.M1 version is higher than 1.4.0.Beta1. That's why the project examples plugin hasn't been updated.
The issue isn't fixed in the 1.4.0.M1.
Try to install Eclipse Juno from scratch and add JBoss Tools using the http://download.jboss.org/jbosstools/updates/development/juno/ update site.