Seriously, the exploit that it is possible to get loans interest free (or whatever that's now called) is known, it is not THAT hard to find out the time when this is calculated every hour and I also have been bitten by this every once in a while - it seems during a rally borrowers just take whatever is there, wait a bit until new lending offers pop up and then take these, cancelling the existing ones. Unfortunately Bitfinex does NOT seem to do interest calculation once an order completes over its lifetime or since the last midnight payment, whatever is shorter, but rather every hour on all active ones, for whatever weird reason.

This would be only fair, not a penalty to pay lenders for at least e.g. 1 hour or 1 day no matter how short in time a loan was taken since again it is possible to end up with nothing. Especially bad if you don't renew loans or don't use autolend and this just gets cancelled.