(a) I had finished sock #1 and it fit well.
(b) I had resisted temptation to put the project aside for something that didn't require such tight tension or focus, thus preventing my WIP/UFO count from rising further.
Cruising along, of course, is a relative term, especially applied to such a fiendish design. I checked stitch count every row, and all was well.
Or so I thought.
Partway through the cuff, I decided to flip my knitting inside out to make sure none of the bobbles was an "innie" instead of an "outie" (if you've knit these socks, you know this can be an issue). I was shocked to find that I had managed to achieve the impossible.
Without making any error in stitch count, I managed to drop two stitches. While ripping back 10 rows and reknitting, I had a lot of time to ponder how I could have done this. My best guess is that the stitches were dropped in a decrease row (I did a k1 instead of a k2tog) and the whole thing held together just long enough for me to miss the mistake. By the time I found it, several more rows had unravelled and multiple stitches were now dropped due to decreases in previous rows.
Or so I think.
Maybe it was just the knitting gremlin getting on my case for being smug.