At 60 FPS, it synchs with your eyes perfectly. Any more makes minimal difference.
You're running it great.
Hmm, I remember back in the days of CRTs, even 90Hz gave a lot of people sore eyes and headaches. I'm just glad that LCD screens don't have the same degree of flicker; I can live with 60Hz (provided there's no tearing), though 40 starts to make me feel nauseous.