[tor-relays] Accounting and the 'Stable' flag

Hello list, I have enabled daily accounting on a non-exit Tor relay some days ago. On the first day, the transfer threshold was reached and the relay entered hibernation for a few hours, as expected. On the next day, I reduced RelayBandwidthRate to ensure that the accumulated transfer would fall just short of the AccountingMax value. During the last days, the relay has only been offline once for a couple of minutes (software update), besides the previously mentioned single hibernation period. As of today, the relay seems to have lost the 'Stable' flag, which I don't really understand. Am I missing something here? I could not find documentation mentioning a relationship between accounting and the 'Stable' flag. -Ralph