I'm pretty sure it has also been there for the Offer post type (I've had the feature built into my WordPress plugin for 2-3 years). But I won't be surprised if Google did a staged rollout on the feature like they did with other features
New advertising option:
A review of your product or service posted by a Sterling Sky employee. This will also be shared on the Sterling Sky & LSF Twitter accounts, our Facebook group, LinkedIn, and both newsletters.