initial serial monitor test . puzzled by response

I understand it works for everybody else. Here is some further tests by adding lines

void setup()
{
  Serial.begin(9600);
  Serial.println(1234);
  Serial.println(5678);
  Serial.println("hello world");
  
}
void loop()
{}

Gives the first Serial output.

If I change the code to print a blank line so that it looks like

void setup()
{
  Serial.begin(9600);
  Serial.println();
  Serial.println(1234);
  Serial.println(5678);
  Serial.println("hello world");
  
}
void loop()
{}

then I get the next result. It's a workaround, but it should not be necessary. Why is my iMac (10.9.2) doing this?

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2014-05-13_1159.png