Why raise version from 1.7.3 to 1.7.5 ?
According to Semantic Versioning (http://semver.org/) it should be raised to 1.8.0, because you added functionality.
If you dont follow semver, it should be 1.7.3 because the current public stable version is 1.7.2. See http://community.opscode.com/cookbooks/memcached