i think it's the quest: the bounty hunt or something in nlc. I find leprecauns dont drop the lucky charms. I killed like 30 of them and only 2 lucky chars :S
So they don't drop, but you can kill 30 or so and get 2?
Hmm..
what i meant is they dont drop it as often. Like how the sakura cellions drop drop cherry blossom branches as much.