How can I keep tick marks from repeating when I have a small number of dates on an nvd3 chart-open source projects novus/nvd3

The x axis likes to repeat dates when there are a limited number of dates. Please see this fiddle:

http://jsfiddle.net/skilesare/bFfJ2/1/

nv.addGraph(function() {  

    var data = fakeActivityByDate();

    var chart = nv.models.lineChart();




chart.xAxis
       .axisLabel('Date')
       .rotateLabels(-45)
       .tickFormat(function(d) { return d3.time.format('%b %d')(new Date(d)); });

   chart.yAxis
       .axisLabel('Activity')
       .tickFormat(d3.format('d'));

   d3.select('#chart svg')
       .datum(data)
     .transition().duration(500)
       .call(chart);

   nv.utils.windowResize(function() { d3.select('#chart svg').call(chart) });

   return chart;
 });

function days(num) {
  return num*60*60*1000*24
}
 /**************************************
  * Simple test data generator
  */

function fakeActivityByDate() {
   var lineData = [];
   var y=0;
   var start_date = new Date() - days(365); // one year ago

   for (var i = 0; i < 4; i++) {
     lineData.push({x: new Date(start_date + days(i)), y: y});
     y=y+Math.floor((Math.random()*10)-3);
   }

   return [
     {
       values: lineData,
       key: 'Activity',
       color: '#ff7f0e'
     }
   ];
 }`

If your screen is wide enough you will see dates repeated. If you sqeeze the window, the problem goes away.