The MLG does not have its own uplock viz 744 but the MLG doors do.However,the gear does not rest on the doors in flight.Now as it looks like the doors were released via the ground ALT release,we may have an issue with the electrical ALT actuator.Perhaps the best option is to wait and see the preliminary report,after all,we can only make educated guess's.I am very sure that this one will not take very long to find the cause.