It's late, but my answer might help other people.
Your JSON should contain the "og:title" like below
{ "og:url": "http://samples.ogp.me/887352634705379", "og:title": "Sample Itinerary", "og:type": "namespace:object_type", "og:image": "https://fbstatic-a.akamaihd.net/images/devsite/attachment_blank.png", "og:description": "", "fb:app_id": [fb-id] }
Now "Sample Itinerary" will be displayed as the name of the pin.