Histogram count issue

gistfile1.js

curl -XDELETE http://localhost:9200/indexname
curl -XPUT http://localhost:9200/indexname
echo

curl -XPUT 'http://localhost:9200/indexname/histogram/_mapping?pretty=1' -d '
{
    "histogram":
    {
        "properties":
        {
            "date1" : { "type" : "date" },
            "date2" : { "type" : "date" }
        }
    }
}
';
echo

for (( i = 1; i < 21; ++i ))
do
    curl -XPUT "http://localhost:9200/indexname/histogram/$i" -d "
    {
        \"date1\" : \"$(date +%Y-%m)-$i\",
        \"date2\" : \"2009-11-11T16:34:34.000Z\"
    }";
done

curl -XPOST http://localhost:9200/_refresh
curl -XGET 'http://localhost:9200/indexname/_search?search_type=count&pretty=1' -d '
{
    "query" : { "match_all" : {} },
    "facets" : {
        "histogram1" : {
           "date_histogram" : { "field" : "date1", "interval" : "1d" }
        },
        "histogram2" : {
           "date_histogram" : { "field" : "date2", "interval" : "1d" }
        }
    }
}'
echo

// #############################
// outputs the following, note the count of 24 in facets!
// #############################

{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 3,
    "successful" : 3,
    "failed" : 0
  },
  "hits" : {
    "total" : 20,
    "max_score" : 0.0,
    "hits" : [ ]
  },
  "facets" : {
    "histogram1" : {
      "_type" : "histogram",
      "entries" : [ {
        "time" : 1301702400000,
        "count" : 4
      }, {
        "time" : 1301961600000,
        "count" : 4
      }, {
        "time" : 1302220800000,
        "count" : 4
      }, {
        "time" : 1302566400000,
        "count" : 4
      }, {
        "time" : 1302825600000,
        "count" : 4
      }, {
        "time" : 1303084800000,
        "count" : 4
      } ]
    },
    "histogram2" : {
      "_type" : "histogram",
      "entries" : [ {
        "time" : 1257897600000,
        "count" : 24
      } ]
    }
  }
}