If you check a file into cvs and then force a build on Hudson within the same minute, the latest file will not get the cvs tag. This can be solved by changing the CgsTagPlugin class.
Change
String date = new SimpleDateFormat("yyyy-MM-dd HH:mm").format(build.getTimestamp().getTime());
to
String date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(build.getTimestamp().getTime());