Found out a coworker with less experience makes noticeably more than me

We were comparing notes — their choice, they brought it up openly — and in the course of it I learned that someone who joined after me, with less experience, is on a clearly higher band. Same title, same team. I know the likely reason is that they negotiated harder on the way in, and that internal raises almost never catch you up to a strong starting offer. Doesn't make it sit any easier; every time I open my editor there's this low hum of "why am I doing the same work for less."

I'm torn between raising it with my manager now, parking it for review season, and just letting it fuel the next move. For anyone who's found out they were underpaid next to a peer — how did you handle it without poisoning how you feel about the place?