Leap seconds need updating.  I get this warning every time I run "z step".  Not a big deal, but it's filling up my terminal windows.

/ligo/apps/linux-x86_64/gpstime/lib/python2.7/site-packages/gpstime-0.1.2-py2.7.egg/gpstime/__init__.py:150: RuntimeWarning: Leap second data is expired.
Run 'update_leapdata()' to download the latest bulletin from the IETF
  RuntimeWarning, stacklevel=1)