Twilight's only had her wings for about a week, only a little shorter than the time since she started dating Rainbow Dash. She's yet to learn how to preen, and Rainbow's willing to help teach her!
Written for One-Shotober.
(As a note, you can get the original source of the picture by clicking it. The original is beautiful and has Fluttershy in it as well, but I had to edit her out (poorly) to fit the story. Please don't hate me for editing her out; she's my second-favorite pone, but she doesn't fit in the story!)