Thing is, you know more about your burning patterns than I do, so when you say that's an anomaly, I have to roll with it, right?
I would like to note, now that you bring it up, CD-DVD Speed is sensitive to background activities, or sensitive to you moving its window around while it's working, even. So if that defrag app actually started to run at any point, it maybe -- just MAYBE -- affected how often CD-DVD Speed was actually taking samples to display. I'd think the actual burn was fine, though.
You could always do a disc quality scan at 12x to help convince you of how well the drive(s) has (have) been handling the layer breaks.
Just out of curiosity, how fast have you been writing the discs, and do you know if they're made in the U.A.E., or Singapore, or Taiwan, or India? Also, is it MKM 001 or MKM 003?