A new audit issued last week by the Federal Housing Finance Agency’s official watchdog revealed that an unnamed nonbank special servicer raised red flags for Fannie Mae, Freddie Mac and their regulator.The report by the FHFA’s Office of Inspector General prompted the FHFA to issue guidance on the counterparty risk posed by nonbank servicers by year’s end. The OIG audit said the Finance Agency and the two GSEs “have responded well to specific problems at nonbank special servicers.”