I dont have a leaf but I know what you mean. I test drove a leaf and the regen braking if you use it right can allow you to stop without using your brake pads or with very minimal use. I had the same thing on my current 2003 toyota echo and it was the rotors were rusted because the car wasnt driven in a while (no regen on the echo
To prevent such a thing from happening u have to from time to time just press the brake harder to get the disks and pads to create friction a little to prevent them from rusting up. (Dont hammer the brakes
if thats not the case then it might b your brake pump (generally they are not cheap for any car out there
I'm just waiting for the 2013 leaf to come here in Canada and see how it is improved for the winter, and if its slightly better than 2012 i am going for 1
untill then my little echo can do the trick for a guy my size (6ft 7in).
Let us know how this works out.