The problems with the Z3801 (and Z3812 / KS23xxx) devices is they expect the leapsecond to occur at the end of March/June/Sept/Dec. So if the leapsecond is announced more than 3 months in advance they calculate the wrong day of the leapsecond. I suspect that they would mess up any leapsecond not at the end of March/June/Sept/Dec. I don't know if the HP53xxx devices have the same firmware bug... After a couple of days after 30 Sep the Z3801A and Z3812A did not show a leap second was pending, so I power-cycled the Z3801A and it started showing the leap pending again. I left the Z3812A running and after 3 days it started showing the proper leap second pending.