Naruto wasn't stupid. But there were a lot of things he didn't know. Mainly, why everyone mistreated him. But also mundane things like how to take care of himself properly or talk to adults respectfully. Actually, in the last instance it had less to do with being untrained and more to do with "giving as good as he got." So he might not have known how rude he was to Yura and just blurted it out. But mainly, he had no reason to think she was going to be nice so he didnt speak nicely to her. That was his habit, honestly.

Afterward though he did feel guilty. But it wasnt like he could take it back. And they left already. So he resorted to being angry instead.

"Well, fine then! I didn't want to talk to you either!" He yelled, though they were too far to hear him. He glared at the rest of the people that had heard and then he loped off in the direction of the ramen shop... The only place he ever felt welcome. 

He was surprised when Sasuke caught up to him. And half expected to be attacked maybe verbally or physically. But instead, the other boy grasped his hand to stop him and smiled a little. Sasuke of all people! The one whose clan was murdered and looked dead himself ever since... But even more surprising than all of that was the invitation that came next. It was literally the last thing he expected to happen. 

He was so shocked that he actually screamed in terror and fell down. Then he just clutched his chest, wondering what on Earth he was feeling right now. These werent emotions he recognized...

When he finally lifted his head he had tears in his eyes. He looked into Sasuke's eyes briefly then quickly looked away. He nodded once.