Camber and Caster 1997 Ford Explorer.

Good Morning; I have a 1997 Ford Explorer 4.0 SOHC 2 wheel drive model. I just had the front end aligned and the front wheels appear to be leaning in. I remarked to the shop technician and was informed that as the Explorers wear (156,000) miles, they have a tendency to do this. Steering is tight and I can't find any play in the ball joints. Most of my experience has been limited to Chrysler vehicles. Any ideas?

Thanks