in_tail wrong time parsing?

gistfile1.txt

[fluentd]
$ fluentd -c fluentd.conf
2014-09-05 10:17:57 +0900 [info]: starting fluentd-0.10.53
2014-09-05 10:17:57 +0900 [info]: reading config file path="fluentd.conf"
2014-09-05 10:17:57 +0900 [info]: gem 'fluentd' version '0.10.53'
2014-09-05 10:17:57 +0900 [info]: using configuration file: <ROOT>
  <source>
    type tail
    tag ltsv
    format ltsv
    path /tmp/test.ltsv
  </source>
  <source>
    type tail
    tag json
    format json
    path /tmp/test.json
  </source>
  <match **>
    type stdout
  </match>
</ROOT>
2014-09-05 10:17:57 +0900 [info]: adding source type="tail"
2014-09-05 10:17:57 +0900 [warn]: 'pos_file PATH' parameter is not set to a 'tail' source.
2014-09-05 10:17:57 +0900 [warn]: this parameter is highly recommended to save the position to resume tailing.
2014-09-05 10:17:57 +0900 [info]: adding source type="tail"
2014-09-05 10:17:57 +0900 [warn]: 'pos_file PATH' parameter is not set to a 'tail' source.
2014-09-05 10:17:57 +0900 [warn]: this parameter is highly recommended to save the position to resume tailing.
2014-09-05 10:17:57 +0900 [info]: adding match pattern="**" type="stdout"
2014-09-05 10:17:57 +0900 [info]: following tail of /tmp/test.ltsv
2014-09-05 10:17:57 +0900 [info]: following tail of /tmp/test.json

[another terminal]
$ echo '{"time":"2014-09-04T12:22:09+09:00","foo":"bar"}' >> /tmp/test.json
$ echo 'time:2014-09-04T12:22:09+09:00\tfoo:bar' >> /tmp/test.ltsv

[fluentd]
1970-01-01 09:33:34 +0900 json: {"foo":"bar"}
2014-09-04 12:22:09 +0900 ltsv: {"foo":"bar"}