On October 15th Danny and I left the interferometer locked with the request set to low noise when we left.  It was left this way from 3:20 UTC to around 13 UTC when Gabriele and Jenne arrived and re-aligned it. Summary page 

There were 9 locking attempts over the 10 hour period, the interferometer made it to low noise 6 times, lost lock once from the state park ALS VCO (currently this happens right after the transition to RF DARM and engaging the DHARD WFS), once while closing the beam diverters, and once while trying to transition the common arms onto the transmitted IR signals.  

The lockloss page makes it easy to look up things like this.  All of these locks were short.