I cast on, knit a few inches, and then learned that Cascade 220 Superwash has a smaller gauge than Cascade 220. Riiiiiiiiiiiiip:
On the plus side, I think that the hem of the cardigan is unflattering and really does not fit the tone of the sweater at all, so I get to restart it with a much more appropriate (in my opinion) edging. We'll see if my idea works - I'm planning to start with Judy's Magic Cast-On, knitting a ribbed border, then doing short rows for the corners to bring it up the fronts of the sweater, continuing as written for the rest of it. Hopefully that works!