Why is my plugin version 0.1?

Your version number in your plugin header.

leaflet-map.php:

<?php
/*
Plugin Name: Leaflet Map
Plugin URI: http://twitter.com/bozdoz/
Description: A plugin for creating a Leaflet JS map with a shortcode.
Version: 0.1
Author: Benjamin J DeLong
Author URI: http://twitter.com/bozdoz/
License: GPL2
*/