I find it sometimes helps to do a row or two of unjoined knitting before joining -- there is a little gap to sew up at the end but it means that you know that it isn't twisted.
This was my second brilliant idea to fix it. I knit like 4 rows and then carefully laid everything down, smoothed everything out...and screwed it all up. Yep. I dunno, maybe I didn't have enough chocolate/sugar/coffee today, but in hindsight that's highly doubtful. Maybe it was all the fault of the sugar rush.