It's possible it's time for a new pump head gasket, if that is where the filter leaked.
I have also experienced a dribble of water coming out of the top hole on the overflow compartment section on occasions. Maybe when the filter filled completely with water due to the power loss, some water escaped out that connection.
It's also possible that there is too much 'head' pressure on the filter when it is powered off due to the distance between the rim of the tank and the pump head. This is just a guess considering the maximum height restriction for the filter.