i dont know how sakura would know being knocked out and all. naruto isnt gonna say openly "hey sakura i saved you" because he isnt a jackass. And same with sasuke because he is too prideful. Not saying that Naruto is stronger and defeated Gaara will maybe help him try to have it so it isnt true. And lastly.. Sakura is stupid and already concludes that Sasuke saved her... so she doesnt ask.