[nznog] NZ NTP servers giving incorrect times?

Hi have just noticed msltime.irl.cri.nz. and msltime2.irl.cri.nz. have developed a 180 second offset from GPS-based ntp sources. As far as we can tell, the GPS-based sources are more likely right than the msltime servers. Can anyone shed any further light on this? cheers, John Rumsey