OK, I checked it out further. The kickdown mechanism is still there and functioning, but the "click" is definitely not as pronounced as when new.
I used my hand to depress the accelerator pedal and could feel some resistance at the kickdown point (you can do this even when the car is off), but the hard "clickiness" that was immediately noticeable when I bought the car is now rather subdued.
Next oil change I'll have the dealer look at it. Worse case scenario if they don't see it as a problem, I can just buy a new one.