An RPM update of Hudson yesterday (to 1.375) prevents the gerrit trigger plugin from publishing the results of a build back to Gerrit. We downgraded hudson back to 1.373, and the problem went away. When the build starts, the "Starting build" message does make it to Gerrit, but though the build completes, Gerrit is not notified of the completion, and manual verification of the patch is required.
Attached is what looks like the relevant hudson log portion. Please let me know if you need anything else.
Thanks for a great plugin!