Not sure about what caused the Lockloss.  DRMI locked up in about 11min (just before I was going to try PRMI).  Everything went smoothly through Guardian steps, except for when I had to Engage the 2nd ISS Loop by hand, I think I was not quite at zero, and this generated an OMC DCPD Saturation (which produced huge dips on many signals on the StripTool...but managed to stay locked!).  Waited for the range to get up to around 80Mpc, and then took to Observing.