grunt-contrib-concat concat goal sourcemap option is not working (windows)

Question

When running grunt concat the console says my source map is created, but the source map is not present on my file system.

My plugin configuration in my Gruntfile:

  grunt.config('concat',{
    scripts: {
      src: [
        grunt.config.get('pkg.src') + '/scripts/vendor/underscore*.js',
        grunt.config.get('pkg.src') + '/scripts/vendor/jquery*.js',
        grunt.config.get('pkg.src') + '/scripts/vendor/angular-*.js',
        grunt.config.get('pkg.src') + '/scripts/vendor/*.js',
        grunt.config.get('pkg.src') + '/scripts/source/main.js',
        grunt.config.get('pkg.src') + '/scripts/source/services/httpHelper.js',
        grunt.config.get('pkg.src') + '/scripts/source/**/*.js'
      ], 
      dest: 'static/server/scripts/app.js',
      options: {
        sourceMap: true
      }
    },
    styles: {
      src: [
        grunt.config.get('pkg.src') + '/styles/vendor/**/*.css',
        grunt.config.get('pkg.src') + '/styles/source/**/*.css'
      ],
      dest: 'static/server/styles/app.css'
    },
  });

Console output:

C:\workspace\someproject>grunt concat
Running "concat:scripts" (concat) task
Source map static/server/scripts/app.js.map created.
File static/server/scripts/app.js created.

Running "concat:styles" (concat) task
File static/server/styles/app.css created.

Done, without errors.

NOTE: I am using Windows 7, Node v0.12.0, Grunt v0.4.5, grunt-cli v0.1.13, and grunt-contrib-concat 0.5.1.