The issue could be a slight amount of filament leaking out during the z-axis lift.. ?? Perhaps try a slightly lower tempurature... do you have any filament oozzing out of the nozzle right before it gets up to temp?

Most slicers have a setting to randomize seam position. Slic3r has it for sure, if that is what you are using. That might be worth a try.

I have some curling problems as well on most parts with overhangs. No idea why. I've only ever tried printing with PLA thusfar, what material are you using?