I'm sure this is not unique to me, but if you go: My Account > Payment History
And look at the calculation of Monthly balance, it's clearly wrong. The problem starts here:
Earnings carried over from previous months
This only happens when View is set to Last 3 Months and I think I found the problem.
Look at the first Payment Issued (Top to Bottom), value in the Payments/debits column. Then look at the first row of data in the Earnings/credits column. The Earnings/credits number is the -2 x the Payments/debits.
Is that Googlenomics or does Google owe me a lot of money? Is it Christmas already?