I decided to knit on, in the hopes that I actually had enough yarn. I knit through the foot - where I found a know in the skein of Jitterbug, unknotted it and knit on. I knit to the end of the sock, weighed it and found that I had used half the yarn. Problem solved. I can relax now, right?
I knit the leg of the second sock and held it up next to the first to see if they were the same length. The same length they were, BUT NOT THE SAME COLOUR. It's pretty subtle,but the finished sock is a slightly less vibrant colour. The socks are different dye lots, even though they are made form the same skein. Yes, the ball of Jitterbug didn't just have a knot in it, they had joined a different dye lot to it. I don;t really have word to express how I feel about this, except I'm glad I don't have any more Jitterbug in my stash.