Is $700 to repair wood rot at subfloor a fair price?

While having my kitchen floors redone with new tile, my contractor found a couple spots of wood rot at the subfloor. The work seems like a small area to me, just behind the refrigerator and stove areas. I initially thought the price was high, but after some discussion, the contractor lowered it, and I'm moving forward with the repair. There was a sloppy handyman who installed something previously, which might be related.