Jan,

There is nothing wrong with your plant. It could be the beginning of what is called "cristate form" or "Crested Adenium".

If the growth grows in a "fan" shape and flat as it is showing, then it will be a Crested Form.

This is a photo that someone posted. Not my plant. Just to show the form.

Rick

Definitely fasciation (fancy word for cresting).

Congratulations, it's pretty rare, and it's usually not hereditary, it's thought to be caused by insect or microbe damage. (it may or may not be in Adeniums, they sell seeds claiming they will crest, but I am skeptical, and the seeds may just be infected or more vulnerable to microbes).

It's not harmful, just an interesting phenomenon