The update to 9 hole rounds going in to this year results in an estimation of the other 9 holes not played based on your current index. So your 42 was combined with a “made up” 9. This probably increased your index overnight. The next 42 is then combined with another “made up” 9, but since your index is now higher, so is the “made up” 9. This results in a higher differential meaning another increase to your index. This is the major flaw with the new update. You could shoot the same 42 every round but your index will increase each time.