Moondancer did smile a few seconds later. It’s not the same with Zephyr at that point of the episode.

Rainbow Dash chciała chyba powiedzieć  
‘‘Po****ło cię Zephyr?’’.

@Ihhh  
Fair enough. What does it mean to you? What stretching are you prepared to do to justify your own conclusions? The episode tells us very little, after all, you can choose to interpret that scene as… well, something else than a first meeting?

@Background Pony #A097  

 
How? You’re really stretching to prove your headcanon, because you’re begging the question and making conclusions without directly connecting them to their premises.

@Ihhh  
Fluttershy: All right, little ones. This way. This way. You really should be more careful. Somepony could get hurt. Why are you in such a hurry anyway?  
Scootaloo: We’re trying to find Rainbow Dash, so we can hear how she earned her cutie mark.  
Fluttershy: Oh, that would be interesting. You know, I wouldn’t have gotten my cutie mark if it weren’t for her.  
Scootaloo: Rainbow Dash?! Really?!  
Fluttershy: Oh yes. It all started at Summer Flight Camp.
 
Fluttershy: [voiceover] You’d never guess, but when I was little I was very shy. And a very weak flyer.  
Young Fluttershy: [yelping]  
Young “Dumb-Bell”: [laughter] Nice going, “Klutzershy”! They oughtta ground you permanently.  
Young Hoops: Ha! My baby brother can fly better than you!  
Fluttershy: [voiceover] It was the most humiliating moment of my life. And then, out of nowhere…  
Young Rainbow Dash: Leave her alone!  
Young Hoops: Ooh, what are you gonna do, “Rainbow Crash”?  
Young Rainbow Dash: Keep making fun of her and find out!
 
That’s direct from the transcript. Out of nowhere implies Rainbow had never done this before, in all likelihood because this is when they met. As foalhood friends, of course Rainbow would come by to visit. So… yeah, they met on the same day they got their cutie marks.

@Background Pony #42E2  
Not only did they not meet then, Fluttershy is part of the events that got RD her cutie mark.  
They must have already known each other.

@Background Pony #42E2  

 
Um, no. Where did you hear that?

@Background Pony #42E2  
…m’kay, man.

@Background Pony #1399  
Well, think about it. Rainbow and Shy met when they both got their cutiemarks. Rainbow would have been invited home, and I have no doubt met Fluttershy’s little brother. Then Zeph discovers he has a penis and starts hitting on his sister’s best friend. It would be awkward at first, then annoying.

@aerion111  
hmmm…yes, Ship Twilight and Dash. Then Find Moon Dancer a stallion. The mooch can forever be alone

And a Twi and Zeph alliance is born.  
“You help me get a date with her, I’ll help you get a date with her.”

@Background Pony #42E2  

 
the more you know

@Toxicpinkiepie  
There’s clearly a very obvious solution here :P

The difference being HUGE in context. Moondancer and Twilight were reconciling after Twilight estranged herself from ponies who valued her friendship when she didn’t even think of them as being close.
 
Rainbow and Zeph essentially grew up together, she’s been putting up with his bullshit for years, and is getting tired of it.

Twilight: shhhh, give into the lesbian feelings.
 
Rainbow:eeeeewww, get off, I’m a lesbian.