The problem is, the barrel is torqued in place.
If you just turn it back so the sight is centered, you break the torque and the barrel will then probably be loose enough that firing vibration will cause the barrel to unscrew.
This usually means the barrel has to be re-set by setting the barrel back by one thread. This is NO job for most local gunsmiths, most of whom don't have all the tooling to do it right.
Most of them will just back the barrel off slightly, and hope the barrel doesn't unscrew later.
Then too, without the right tooling, many locals my be tempted to use a hammer handle instead of a frame wrench and could ruin the gun.
My suggestion, either find a REAL S&W qualified local pistolsmith who you know for sure has the tooling, or send it in to S&W to get it done right.
I suspect that S&W has methods of tightening the barrel so they don't have to completely rework the barrel.
Possibly, since it's a factory mistake, they may do it for nothing.