Because naruto doesn't think well when sasuke he is arround. He is doing way worse than before sasuke's arrival, the only thing he is doing is yelling "SASUKE". I don't know why kishi does this to naruto.
It's obvious he's in love.
People can't think straight when they're in love.
Seriously though, Naruto may be faster than Sasuke, but his reaction time is slower.
Naruto doesn't have the Sharingan like Sasuke, so it's natural that this would've happened.
Even if Naruto saw it, he was in midair. He would have to use a Kage Bunshin or extend a chakra arm. It takes time to do it...
But basically, it's like this:
Naruto saved Sasuke two chapters ago...
Sasuke saved Naruto...
It's fair.
But Naruto needs to stop saying "Sasuke", it's annoying.
Why would Kishi make a panel just to make Naruto say "Sasuke"?