good question! the same thing happened to a pair of mine, (4.5 mm). I thought I did something to them to make them warp or that maybe it's what happened to bamboo needles after a lot of use, it's one of my first pairs that has had soooo much use.
but all the same I found it a bit annoying, so I am glad to know there is a way to fix it.
"Failure is only an opportunity to begin agian more intellegently." When Henry Ford said that I doubt he had knitting in mind, but if the sweater fits...
I just look a my bent needles and smile. One finally broke in half and I kept the pieces to use as aids to hold sts out of the way, if ever needed. Can you tell I never throw anything away? They were my size "0" and the shorter length, which I love. Now I am going to have to buy a new set of the short ones. I have loads of the longer ones. Yes, I have thought of "shortening" one or two of the longer ones.
Sharon in NW PA I always wanted my own library but I didn't realize it would be all knitting books!