There are only 3 reasons for all tires to wear out prematurely on the inside:
inadequate tire rotation
out of alignment
We can rule out the tire rotation as it is done well within recommended schedule. That leaves 2 other reasons.
Simple check for the struts/shocks. Push down on each corner of vehicle. It should go down once, rebound up and stop. If it goes down again and back up and stops, then the shock/strut is bad. I doubt that all 4 are bad with 23K miles on it, but go ahead and do this check.
If ok, as I suspect, then alignment is out. Most likely the camber. Camber is how the wheel sits on the vertical, either leaning in towards engine at the top, or leaning away from car at top. Generally when the camber is out, the vehicle wont pull so you wont know it, except by premature inner tire wear.
I dont know why car manufacturers never put this in their maintenance schedules, but all vehicles should have their alignment at least checked once every 6 months. this is because all it takes is hitting one pothole, going over railroad tracks fast, hitting one curb to knock it out of alignment.