Grooves on Only One Brake Rotor

Thanks in advance for looking at my question.

2006 VW Jetta. Driver's side rear brake rotor, the inside of the rotor, is the only place where grooves have been worn into the rotor. The passenger side and both front rotors are fine. Does that indicate a sticky caliper, or other problem?

Thanks,
J

you might want to see if the e-brake cable is dragging on that side