OK, the issue has been corrected in the download package.
The problem here is that the plugin has been compatible with WP 3.1 and up in the past and I’ve never instituted an official policy on WP compatibility.
Starting with 2.9.0, which is expected to be the next release, I will be instituting a more official policy of WP version support for the plugin. This will probably be supporting the current major WP version and one major version prior. For example, at present, WP is version 3.7.1, so we would support WP 3.7.x and 3.6.x.
Whatever is decided will be included in the release notes. But WordPress site management best practices would dictate that it is a very bad idea to continue to use outdated versions of the software.
With that in mind, it is a break from protocol to change an update, but this was an unintended issue. Obviously, it is not going to effect any users with WP 3.6 and above (which I certainly would hope would be the vast majority of users). But because there wasn’t an appropriate announcement alerting users to the coming shift in compatibility policy, I feel the need to accommodate that.