Amplification from the additional Rref Is Very Annoying

I'm using AD8222 in my sensor design where it is used to interface with Wheatstone bridge. On the prototype, +IN1 and -IN1 are tied together to fix 2.50000V.  +Vs is set to 12.0v and -Vs is set to 0v. REF1 is tied to a unity buffer op-amp (REF495) with a voltage of 2.5V. The gain setting is 351 with RG1 set at 141 ohm.

Theoretically, i would expect the OUT1 of 2.50000V. However, there is always an additional amplification of 0.02V. I suspect this comes from the amplification from the additional Rref. How can i get rid of the additional amplification of 0.02V. i attach the circuitry of the design.