After reading through the posts, I feel like I discovered a new missbehaviour of my jag.
I had all doors closed and drove for 2minutes, than locked the car normally with the fob. ( no double-locking)
When unlocking with Fob, the lights flashed as expected and the unlocking sound could be heard.
Then the gremlin came and locked the car again.
I tried unlocking 5 times, but the gremlin locked the car directly after unlocking.

Opening the car with the key directly in driver's door worked and the gremlin is gone since...

Did you every experience this kind of missbehaviour ?
What to do ?

 

A Gremlin in the fob (the lock button making continuous contact somehow), rather than a car gremlin, maybe ?

 

I changed the fob's battery. ( Old one had 3.1V, which I suppose to be still ok)
The buttons seemed to be ok..Let's see if the gremlin shows up again.

 

Possible answer here:

https://www.jaguarforums.com/forum/g...nition-124443/