I ended up adding i-cord around all edges and across the back (from one armhole to the other),
After the i-cord was applied, I blocked the ribwarmer a second time. The corners and back vent weren't laying as flat as I would have liked, but blocking took care of that problem just fine.
If I make another ribwarmer (and that's a real possibility) I will reduce the number of stitches by up to 5 on the fronts and will make it several rows longer.
Other knitting news -- the Kai-Mei socks might be finished yet today. I have started decreasing for both toes so the end is in sight for this project. The Coco Panel cardigan, however, has taken a turn for the worse. Yesterday I finished the first front side panel and attached it to the corresponding back side panel via 3 needle bindoff. Looked great. Then I held the shoulders together, to get an idea of how that seam will look once sewn, and that's when I discovered that the back is one or two rows wider than the front, and my colors are wrong. I am going to have to rip out the entire side panel and start over. The reknitting won't be difficult, but I am not looking forward to picking up the 125 stitches a second time -- of course that was where the color mistake was made.

