Hi! After making this recipe with several different flavors, I also noticed that it would get oily if I worked it a long time with my hands, probably from the butter staying melted from the heat in my hands. Next time you could try using softened butter instead of fully melting it. I found that if my kitchen was not too hot (64 degrees F) and I worked quickly, it was fine. Did you try putting the candies in the fridge after? I wonder if it became less oily when the butter solidified.