Loosen the grub screw that holds the trigger onto the pin, move the trigger away from the place it's rubbing then tighten the trigger again (after doing what ainsley said). It could be that it's not aligned on the pin, if it's anything like my ego trigger.
ok ive just taken the trigger out and looked at where its rubbing, and there seems to be some execs metal that hasn't been machined off, i think thats what's causing it, probably just needs to be filed down a bit.