This can be a result of know bug BG 2426726.

For example:  you have a pledge and then you make a TP payment to it from another account.  If you then adjust that TP PP to change the Gift Date, the paid amount on the PL ends up being incremented up by the payment amount again, so the paid amount exceeds what has actually been paid. This paid amount is also reflected on the soft credit PP with the new Gift Date.

This will look a bit different if it causes an overpayment and "Auto Adjust Pledge on Overpayment?" is set to Y. When the AC adjustment occurs on the PL to increase the pledge amount up to what the paid amount reached, this will ALSO recompute the paid amount so that it goes back down to normal, but leaves you with a pledge amount higher than what it originally was and the pledge is still marked as fulfilled even though the paid amount does not match the pledge amount.  

Example:  you have a $100 OP PL that has been fulfilled by a single $100 TP PP, you adjust the Gift Date on the PP, this then ups the paid amount on the PL to $200. That then causes an AC adjustment to raise the pledge amount to $200, but also happens to set the paid amount back down to $100. And it leaves the pledge status as FF.

This inflated paid amount can be corrected by making any adjustment to the pledge, which will prompt the paid amount on the pledge to recalculate to the correct amount. However, if there are pledge schedule records for the pledge, then you will get GM333 error trying to adjust the pledge, in which case you should contact TA Support for assistance.

If the pledge got overpaid by the adjustment, prompting an AC adjustment of the PL correcting the paid amount, then you just need to adjust the PL to set back down the pledge amount to the original amount.