(Jordan V., Gerardo M.)
The instrument air at X-End has been alarming, see entry here.  After looking at the trends for this channel, there is some noise/spikes noticeable for this particular channel, while the IFO was recovering from a lockloss, we vented the line but no change was noted on the signal, we will continue to look into this, for now we have raised the alarm level from 5 to 10 via probe, so this is not permanent change.  Perhaps a bad sensor or wire.