Yesterday, I found a link on the German "Porsche Fan Forum" (PFF.de) that pointed to this Press release on the 'Porsche.com/germany' website (link: [url]http://www.porsche.com/germany/aboutporsche/pressreleases/germany/?pool=germany&id=423415[/url] 

It states the following: 
"Porsche is checking worldwide 16,429 vehicles of the models 911 Carrera as well as 718 Boxster and 718 Cayman, 2,576 of which in Germany. On the affected vehicles the screws connecting the fuel collection pipes could possibly come loose. The service departments will replace the mounting bolts with optimized screws. This is merely a precautionary measure."
The last sentence sounds rather soothing, since additional sources in the German automobile press indicate, that, if these screws fail, fuel can run out over the potentially very hot engine block and constitute a fire hazard.

I called Porsche USA in Atlanta, and they confirmed this. The recall reached them this past Monday, and they are presently preparing the recall letters (my car is part of the recall).
They did not have an exact date as to when the bolt replacement can start, since they are still waiting for the required parts.
On the German Porsche Fan Forum I learned that this is not a quick and simple measure; the required worktime at German shops is indicated with 6 hours.

If anybody wants to check if this applies to their vehicle, the Porsche recall number is: AH01

For the U.S., here is a link to a file on the NHTSA website, which identifies the VIN number ranges for affected Porsche models:
[url]https://static.nhtsa.gov/odi/rcl/2017/RCLRPT-17V054-4947.PDF?_ga=1.38798187.916078202.1489276415[/url]

Greetings, Rainer