I recently learned that there was a recall of Dahon folders from 2008 for bicycles without the Radius handlepost.
Here's one of the recall notices:
Dahon and REI Novara Folding Bicycles Recalled Due to Fall Hazard | CPSC.gov
The recall notice mentions only 25 reports ("complaints").
If you had your handlepost replaced, please share details and a picture of the new part if possible.
I've been trying to communicate with Dahon about this but I have the distinct impression that they do not want to provide any service.