I think the situation is a little less alarming than it first appears - the Fed has control over the level of non-borrowed reserves in the system. This is the basis of its permanent open market operations, which 'permanently' add or drain reserves via treasury buying or selling, respectively, unlike the TAF facility and repo activity, which are loans of reserves.
What has happened recently is the banks have been scrambling to get poorly performing assets off their balance sheet, thanks to the 'gracious' bail-out action of the Fed in allowing an exchange of reserves for low-quality collateral via the TAF.
If the Fed loaned all those TAF reserves without draining non-borrowed reserves, the Fed Funds rate would be lowered beyond their target rate. So they redeemed a bunch of treasuries, which reduces the amount of non-borrowed reserves in the system. So effectively there has been an exchange of borrowed reserves for non-borrowed reserves, but the banks have been temporarily relieved of some of their poor quality collateral, which the Fed is holding in cold storage.







