Vibration while braking

2019 Forester Limited with 48k miles on it. I replaced front brake pads and the driver side rotor was clearly warped so bought OEM from local dealer. Pads actually weren't as worn as I thought. Passenger side looked and felt pretty smooth so I left it (I know, they say do it in pairs). So I'm debating replacing the passenger side. Just wondering the likelihood that will fix the problem, versus putting in the effort to replace/inspect both rear brakes, since they don't wear as much as the front do. Thoughts? TIA!!