I agree with James. Within the range he mentioned, stability is more important than any particular number. Rapid, large swings in pH are stressful to your tank inhabitants. Be aware, however, that pH changes throughout the day, with it peaking about lights out (or shortly thereafter) and bottoming out just before lights on.
Also, 2/10-3/10 swing during the course of a day is not unusual, but many reefers use different methods (nighttime kalk additions, reverse light cycles in refugiums, etc) to try and minimize this swing.
FWIW,
Kevin