I was chugging along, a little less than halfway up sleeve one, when I started looking at it. It looked a little narrow. So I laid the ruler on it and lookit that - the gauge was off. I knit the swatch one day, and the sleeve the next and THE DAMN THING WAS OFF BY ALMOST A STITCH PER INCH.
So I washed it.
Knit-purl stitch patterns like ribbing or cables or fluffy stuff like this one can relax quite a lot when they hit water, and I'd washed the gauge swatch, so I figured before I completely freaked out, a trip through the sink was a good idea. You can see I left the ball attatched; just put some (cotton) waste yarn through the stitches and chucked it in the drink.
After it dried, I laid the ruler across it and had another good look.
The gauge is tight at the bottom/cuff, and loosens to what it's supposed to be (according to the gauge swatch) up near the top. I suspect the cuff hem is pulling things in a bit, which is fine, 'cause that's what cuff hems are supposed to do.
For those of you who are relatively new knitters (I just typed 'knew knitters', I really need to get a grip), this is probably the fastest, easiest way to get a solid idea of what's going on with your gauge while you're in the middle of knitting something. If you use plastic or aluminum needles, you can even wash it right on the needle; I couldn't do that today because I was using a wood needle.
But next time I'm taking a BEFORE measurement of my swatch, and totally avoiding the situation. (See? Long-time knitters are still learning stuff, too. Often really obvious stuff.)
Bah. What a waste of a day's knitting.