Odd behavior in member function... or is it?

Riddle me this, Batman...

In my game, I have just built a class to handle user input and has some GUI element (or will eventually have fully realized GUI...)

I encountered this strange behavior:

 class MyClass(){
   //...constructor
   //...properties
   myText : String; //assigned in an init member function
   //...member functions
   function MyDraw(){
     print( "class draw" );
     GUI.Label( Rect( 0, 0, 300, 12 ), myText );
   }
 }
 
 //an instance of myClass is created and assigned to a variable,
 //then initialized all in OnStart()
 
 function OnGUI(){
   print( "OnGUI" );
   myInstancedClass.MyDraw();
 }

So what happens is, the console shows "OnGUI" printed as expected, but "class draw" is NOT printed-- but the GUI.Label call executes because I can see it on screen.

This threw me because I thought the class function wasn't getting called until I put a test string into the member variable to see if it appeared on screen. So, just the print() inside the member function isn't being called??

What's happening here-- help me understand.