There is a slight gap between my upper ball joint and control arm. It is on the driver’s side. The passenger side does not have this gap. Not on the side of the boot but the top of the ball joint as pictured below.

I did the ball joints done about 500 miles ago

should I Be worried about this?

 

did you forget to put the circlip back in when you replaced the ball joint, or perhaps it wasn't fully seated ?

 

Yep, definitely need to make sure the circlip is in there. Better get that taken care of before the balljoint falls out and you end up with a hell of a problem...