Why does a brushed DC motor current draw differ with direction of rotation?
Because motor coils are inductors, it takes a bit of time for the field to build up.  Thus, for high-speed use in one direction, you can bias the position at which the commutation happens with respect to the magnetic field.  If the commutation leads a bit, the motor will generate more torque for the motor current, and it'll go faster -- in that direction.
That's probably what is the case here, either purposefully, or because it's a cheap motor without well-controlled build standards.