How do I find out what happened on this flight? On 2017-01-03 DAL58 from Boston to London apparently returned to New York after 90 minutes of flight.

This seems quite irregular to me, and I had expected to find details about this published somewhere. I tried Google, and I searched at avherald.com for the date and also for B763, but didn't find anything.

Was this not sufficiently irregular to warrant some kind of public information about what happened on this flight? Or if such information is published, where could I find it? Or is such information only available to certain people?
Issues in flight are more common than we think: engine shutting down in flight, fumes in cabin, ... Aircraft are huge pieces of engineering with many parts and sensors that can fail. Aircraft have many redundancies which most of the time allows for a safe landing. 

I tried to look on the avherald, a reliable and extensive source of aircraft reports, incidents and accidents, mainly fed by its owner and its users but the flight does not appear there. However you can appreciate the number of incidents occurring every day and this is a small part of them.