Excessive inner brake pad wear

2002 Astro AWD VIN# 1GNEL19X32B142652

After hearing the brakes the other day, I removed the front wheels and inspected them. I found both driver and passenger inner pads worn down to the metal plate. The outer pads still had 1/4 inch of pad remaining. Thus, I never heard the pad-wear warning squealers alert me to any wear issues. I had the rotors turned/resurfaced and replaced the pads.

Other than lubrication to keep the calipers "loose" and floating, is there any other factors that can contribute to such abnormal wear?

Again, I thank you automotive forums for any and all help.

bad brake calipers , rusty piston bores ,won't allow piston to retract fully after brakes are applied. i would replace with new calipers not rebuilds , and replace all the brake fluid with a D.O.T.3 Synthetic Brake Fluid....make sure you check the caliper brake hose's condition when doing calipers...bleed brakes starting from right rear wheel , then left rear wheel, then right front wheel, then the left front wheel last..make sure you remove all old fluid. you can syphon out the master cylinders old fluid. and refill with synthetic when you start bleeding lines,,,, exwldr.......:sunglasse