4chan API, 403?

Why does the 4chan API return 403 in code but if I hit it directly in my browser it's fine?

Any ideas?

        url = 'http://api.4chan.org/b/1.json'
        userAgent = 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:22.0) Gecko/20100101 Firefox/22.0'

        headers = {'User-Agent' : userAgent}#'Accept-encoding':'gzip'}

        request = urllib.request.Request(url, headers = headers)
        response = urllib.request.urlopen(request)
        html = response.read()

        print(html)

>>16
Go away princess. Go far far away.