The loophole was first spotted by the eagle eyed folks over at the Financial Times, but it is nice to know that such a loophole was discovered so early into the game, considering Google+ is still in limited trial, with users finding some rough edges in the process.
Google stated that “we’re actively listening to feedback from our testers. Prior to launching the product, we may make adjustments to the system in response to this feedback.”
In the mean time, just disable resharing by clicking on a button which appears the moment a post is published, although there is no universal “shut off” feature to overcome this. Just goes to show that even behind the relative anonymity that the Internet provides, you still got to be responsible for what you post.