All Systems Go:
You are correct, the bug wasn't found until the day shift started splitting. However the low level code data logs do show the session problems from when that workstation was booted up at about 0120Z.
One thing to note, this problem was not caused, nor affected by the DD&C. It is a problem which sometimes appears on a workstation re-start, it could happen at any time when there's a re-start.
Not sure if you thought I was infering that the NATS Engineering staff (the word technicians is obviously an emotive one!) skills and abilities were anything other than excellent. I apologise if I came across that way. This problem was not identified until a couple of CXSS experts sifted through the low level code data logs and spotted anomolous activity. Not something which would generally smack you between the eyes and not something monitored in system control.