I think kelkyag has the right idea. I don't think the line between craft and art is a clear or simple one, and I think calling something a "craft" often belittles the skill of the creator. Unless you are following a pre-established pattern and just copying it, even making an Anubis mask you've made a dozen times before is art. You may not have put much thought into the masks you made last night, but that's only because you've made them so many times before and you know what you are doing.

People call my beadwork art all the time, and yet once I have the pattern in my head much of the actual beading process is rote--but the hard part is the original design and choosing the beads--colors, textures, etc. Your leather work is similar. The art lies in the design, the choice of colors and the carving etc. Even if the actual execution is sometimes by rote, it still requires skill and being able to translate that image in your mind into the leather--and that makes your leather work art.