Several times when I slam the trunk shut I hear a click and the trunk opens itself. Anyone have the same issue?

 

I had a spell of that once, months ago. Gave me fits for a minute or two, then finally latched. Hasn't given me problems since. Tried to figure out how to replicate it to show the dealer, couldn't get it to act up. I know what you're talking about and it's really really weird. Did you eventually get it to stay closed?

 

Was your trunk full when this happened? Was there something right at the back? I had this happen before and it was where I had a large box pushed all the way to the back that it engaged the release handle at the back, located near the trunk pass thru.. See if something is engaging that.. Hope it helps

 

Other things to consider is that perhaps you stood too close to the car, and it thought that the intelligent key was locked inside the trunk of the car, thus it reopened the trunk so you can retrieve it.
By any chance did you hear a series of beeps after it reopened itself?

That, or that your car has a mind of its own and dislikes you when you "slam" it down. So it's kindly asking you to re-close it gently.

 

I close the trunk the same every time, so proximity to the trunk is not the issue. It takes 4-5 attempts before the trunk stays closed.

PS you definitely hear a click after the trunk is closed that opens the trunk again.