" I'm still not sure how I managed to do that, though." I wish I had a dollar for every time I've said that about my knitting. I could probably buy a house!
I'm glad you see what happened and so can watch out for it next time. I know what to do, make sure the working yarn is on the right needle, and still do it once in a while.
Will you redo it or call it OK, say, Gee, I meant to do it like that?
You might wonder why I recognized the problem. I've not switched to dpn and had it happen but have changed to different sized needles and done the same thing. Whenever something is being changed my opportunities to mess up are greatly increased. If I had a dollar....