Interesting.
I have used time in a script here http://forum.mikrotik.com/t/black-list-for-failed-login-to-ipsec-vpn/130090/4 to get a 5 min window.
Problem with the standard time function is that it only gives hour, but when it passes midnight it uses full date/time.
This may resolve it. Have requested MT for a full epoch time system.