This is not a bug in the plugin. It's because the Jenkins user cannot see the `patchset-created` event (it's visible only to the change owner) and there is no publicly visible event sent when the change is published (moved from DRAFT to NEW status).
I've filed a bug report [1] and I have a patch on Gerrit that fixes it. It'll get uploaded to gerrit-review later (hopefully today) after passing internal review.
[1]
http://code.google.com/p/gerrit/issues/detail?id=1437--
David Pursehouse
Configuration Manager
Sony Mobile Communications Japan, Inc