Have you had your alignment check lately? Hows this for a solid reason? Knee pain. The following study was done with 3000 people. That's a pretty good sample size. The findings:
70% had a leg length inequality.
14% had a leg length inequality greater then 1cm.
Those in the 14% group ended up having significant radiographic and symptomatic evidence of osteoarthritis.
The OA was more significantly found in the shorter leg.
It was also able to predict 30 months later symptomatic knee osteoarthritis.
Keep your pelvis level, your hip abductors strong and your legs lengths even. Your knees will thank you.
Harvey WF et al. Association of leg length inequality with knee osteoarthritis: A cohort study. Annals of Internal Medicine 2010; 152: 287-295.