To be honest, I doubt he can even feel the 2 degree difference if that's what you're worried about. I mean, when we go outside, do we feel the difference between 78 and 80 degrees? Probably not.
There is a large debate as to what temperature bettas should be kept at. As long as they are in the 76-82 degree area and temperature swings are to a minimum he should be fine. I keep one tank at 78 and another at 80. All depends on the heater, if the light gives off heat, etc.