There are some cultivars that seem to grow that way too. Rick pointed one out to me at the garden last week.
I don't have the problems with the severe cold weather here...but there may be multiple causes. I had had lots of them bend over, especially this year, but I don't remember seeing any with that odd breaking pattern. The more I think about it the more I think they snapped for some reason and as the ends dried they curled outward as though the outer 'skin' tissue dried faster and shrank more than the inner tissue.
