@r0BSCENE  
Poor compression algorithm.

“Ohmahgosh, mah butt looks so cute!”

@r0BSCENE
 
Now I see what you mean. I didn’t think you meant it this seriously and thought you were just making a joke, knowing why it really blinks here.  
It’s blinking because it’s a gif. The creation of a gif always comes with some quality loss of the original picture and changing colors, which is what’s causing the blinking here, can happen due to that.  
Her cutie mark didn’t actually blink in this moment (unfortunately, that would have been awesome!).

@r0BSCENE  
Oh, well in that case: TO THE MAP! ;)

@TheOtherPinkiePie  
At the end of the animation the apple in her cutie marks starts blinking between red and purple. I actually don’t know what that means. I just wanted speculation from everyone.

@r0BSCENE  

 
Is there supposed to be a picture I’m not seeing?

@Flareblitzfury
 
Indeed. Very cute.
 
And that other thing too. :3

D’aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaawwww! So cuuuuuuuuuuuuuuute!

@r0BSCENE
 
I would love it so much if that would happen. And with the way they got their cutie marks, it wouldn’t be a surprise if it does.

Oops, Apple Bloom’s cutie mark is blinking. We all know what that means: