Reuters has updated yesterday's story on Citadel. The new iteration includes the following paragraph, which seems to downplay counterparty discussions (by noting that KG isn't alone in his trubs):
The Fed has been speaking with dozens of prominent hedge funds and their counterparties in the past weeks to monitor trading and liquidity issues as the financial crisis deepened, industry sources have said.
Apparently, such discussions are a regular feature of the Fed's monitoring practices, especially over the last several months.
CORRECTED - UPDATE 2-Fed questions counterparties about Citadel [Reuters]