Problen with collision events when changing rigidbody to iskinematic

Hi,

i have a problem where i get unexpected calls to OnCollisionExit when my player "enters" a vehicle.

My whole scene and all objects within it are inside a giant sphere collider and i have a script that deletes all objects leaving it like this:

 void OnTriggerExit (Collider other)
 {
         Destroy(other.gameObject);
 }

This is supposed to delete objects falling into infinite space.

So far, so good.

Now, i wanted to attach the player to a vehicle, using a "VehicleControls" script, that basically does the following:

 ...
         player.transform.parent = playerPos; 
         // playerPos is a GO on the vehicle where the player should be placed
         player.transform.localPosition = Vector3.zero;
         player.transform.rotation = playerPos.rotation;
 ...
         Rigidbody rgbPlayer = player.GetComponent<Rigidbody>();
         rgbPlayer.velocity = Vector3.zero;
         rgbPlayer.isKinematic = true;
 ...

Upon setting isKinematic, OnTriggerExit on the delete script is called and removes the whole player object, which isn't supposed to ever happen, and i get nullpointers in all kinds of other scripts.

A debug log shows that at the time of the event, both the vehicle an player are clearly inside the collision sphere.

What the hell is happening here?!