I noticed DIAG_MAIN flashing "BRSX C code has stopped" after we got back to low noise. I looked at the BRS and it all seems to be okay, its just the H1:ISI-GND_BRS_EMTX_CBIT channel that isn't very stable, see attached.
Perhaps coincidence, but in the DIAG_MAIN logs, the last time this happend was after we reached low noise 2 locks ago (~2:30 UTC).