makes thrown runtime exception rollback the transaction

In code called from a Seam bean I have:
newProxy = session.publishDocument(docToPublish, sectionToPublishTo);
//following code throws an exception
newProxy.setProperty("dublincore", "title", "newName");
session.saveDocument(newProxy);
session.save();

the saveDocument throws an exception because no such change is allowed on proxies.
The proxy is still published when I would expect the transaction to be rolled back and so the proxy not published.