Your average was 63.95 when you wrote this and it is now 63.93. There is only one score I can see that could have caused this drop, the 65 at St Andrews.
It will be something like: 63.95 included 2,558 strokes, the 65 will have replaced a 66 so knocks one stroke off your total which then gives an average of 63.925.
Another way to look at it is when you get the total strokes included to 2,520 your average will then be 63. This means 37 strokes to lose but a 31/62 will knock 2 (or three for now) off that every time you can get it. The odd 30 would be very helpful :-) Good luck.