We just had the same thing happen in Canada with Toronto Dominion Bank as Customer account acessability complaints were initially waved off as a minority of random customers but the sheer volume was nation wide. By the time I logged in the issue was resolved but the news along with the National Banking watchdog's OFSI recommendation of raising Cash reseves up to 5% suggesting worries about cash runs.
Hmmmm... ouch, 5% cash reserves seems a bit tight for internet-speed bank runs. I guess you can always have digital "maintainence" to help slow down the bank runs, but it isn't really a great solution to match archaic rules with internet speed.