What was actually the first line Dumbledore? My theory

 WHAT WAS THE FIRST LINE OF DUMBLEDORE?

When you say the first line of dumbledore you would say 'his first line was fancy seeing you here professor Mcgonagall'. But I do no think that's true.

So when I re-read the Harry Potter seires I noticed something. In the first chapter of the first book when Dumbledore comes to bring Harry to the Dursleys he saw Mcgonagall. Guess what it said? It said in the paragraph it said : For some reason, the sight of the cat seemed to amuse him. He chuckled and muttered "I should have known". Notice that he said " I should have known. 

Those first words were before his words "Fancy seeing you here professor Mcgonagall". I still have no idea why people think that his first words were Fancy seeing you here professor Mcgonagall because it's not. 

If you still think I'm wrong read Harry potter and the philosepher's stone page 9. The full page. Ok why do I sound like Mcgonagall? And if you haven't read the seires READ IT IT'S SOOOO AMAZING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 

Well anyways bye!!!!!!!!!!!!!!!!!!!!!!!!!!!