You've got me thinking. All those moons ago, before you discovered the ball joint needed doing, was much of your riding in town or out of town/longer, faster roads? k
I replaced mine a couple of months ago. Like a new GS now.
Bike became extremely "light" at the front cruising at higher speed (from and over 100mph).
I started losing confidence with the bike while leaning as it started "falling in" over a certain lean angle.
I realised something was very wrong (and that it wasn't my fault) when I started having some serious issues in between subsequent corners at a decent pace in France this summer (bike was very unstable).
There was a tear in the ball joint rubber. Also I bumped in the rear of a car some time ago. It was in pretty bad conditions when we replaced it. Apparently I adapted slowly over the increasing worsening of the bike's "rideability" until it was too much.