"Linen stitch pulls in dramatically as the work progresses".
This would be due to the bar of the slipped stitch, and would be exacerbated by a tight knitter. I found myself working tighter than I typically do, just because of my psychological discomfort with the larger needles.
"You will find that the resulting fabric is stable when dry, but quite flexible when wet. You may find that with wear, the fabric may grow in circumference; with wet-blocking you can shape the fabric back to its original proportions."
These statements really got me wondering, so I dug through my stash for more "emergency" sock yarn skeins and knit another swatch on US 6 (4 mm) needles. My needle size choice was driven by a simple consideration of the linen stitch - each stitch has to span two rows, so I used a needle size that was twice the size of what I might have used in a normal stockinette stitch garment.
So, I'm going to frog what I've got and cast on again on the US 6 needles. I've got to say, I love the colors. They just make me smile.
Pattern: Morphology by A. Karen Alfke
Yarn: Blue Moon Fiber Arts Socks that Rock Lightweight in Sprinkles and Shannanogins
Needle: US 6 (4 mm)