Strange servo behaviour (?)

Hi,

I've got the MeArm recently and I'm trying to control the servos.

It comes with those cheap blue servo motors (sg90), which are depicted in the servo tutorial:
http://www.espruino.com/Servo+Motors

I've tried this simple example just to move a part between two positions in 3 seconds each time it moves.

var s = require("servo").connect(C7);

//s.move(0); // move to position 0 over 1 second
//s.move(1); // move to position 1 over 1 second
//s.move(0.5, 3000); // move to position 0.5 over 3 seconds

// move to position 0 over 1 second, then move to position 1
s.move(0, 3000, function() {
  s.move(1, 3000);
});

My question now:
Is it normal, that as soon as I execute the first move for a specific servo object (even multiple other ones) it will move instantly/quickly instead over the specified time?
After that first move all moves will be executed accordingly.

BR
Daniel