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It's a well known fact that "Star Wars" nerds can be incredibly detail oriented when they put their minds to it, especially when it comes to the costume design. (ever seen the 501st Legion's cosplay reference library? It's MASSIVE.)

So you can bet that when the "Star Wars Rebels" season 2 trailer premiered at Star Wars Celebration this year, EVERYBODY noticed that fan favorite character Sabine Wren went from her trademark indigo and orange hair style...

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...to a brighter teal one instead, and what looks like blue armor decals instead of the orange and pink she was previously sporting:

Of course, as of last weekend's action-packed season premiere, Sabine hasn't yet made any changes to her look -- it's hard to find time to do that when you're being chased by Darth Vader, after all! But it's going to happen soon, says "Rebels" producer Dave Filoni, and there's a super good reason behind the change.

"I don’t believe that people in general that dye their hair ever really stick for it that long," Filoni told MTV News over the phone last week, noting all of his friends who sport unusual hair colors -- including his wife -- like to play around with different shades. "I think it's part of their creative impulse and they're always experimenting and saying, 'What about this?'... As an artist, Sabine would scribble on her armor and change the color of her armor. She would never really settle on this one thing and just be done with it. Most people I know who draw are constantly doodling and changing things."

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But there's another reason Sabine will start looking a little different -- because she's also growing as a person, too. "I think a cartoon character tends to stay the same year after year after year and not really evolve -- but you know, Luke, Han, Leia, Anakin and Obi-Wan evolve each movie and they each have a different look, and the look is reflective of kind of where they are as a character," Filoni pointed out.

For Sabine, "Changing things up has to do with her interaction with Darth Vader -- in that episode she does a pretty bold thing and takes aim at him at one point and fires at him, which doesn’t go so well for her because she doesn’t know who this guy is. So after that attempt on Vader, she gets blasted back and carbon scores her helmet and decides to change up her whole look after that –- kind of a new Sabine after that experience. It’s a line in the sand when she’s like, 'OK, I’m going to do things differently, including changing my hair, changing my outfit.'"

"All of the characters after Vader –- some of them go through more of an emotional change, where they act differently, behave differently –- but they’re affected by this encounter with this terrible Sith Lord."

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OK, I know what you're thinking -- the cosplayers must love this, right? After all, more costume designs means more options when they're attending their favorite conventions! But it also means that the costumes they've ALREADY put so much effort into aren't up to date any more, which can be annoying. Filoni's no stranger to that frustration.

"The Clone Troopers used to get on me all the time, because I used to change up their armor, and I mean those poor guys spent a lot of time and a lot of money to make those things, to make them accurate," Filoni said. "And then they don’t have the latest, newest [version]. You know, so I often think I’m doing everybody a favor and then I see them and they’re all, 'Why Dave, why?'"

"But on a certain level -- I hate to say it, but it becomes fun for me to do that to them, because they’re all such great people,' he acknowledged. "I’ve been at LucasFilms for about a decade, so you know, you go to every convention year after year like I do, and you know a lot of them by sight. You know the costumes they have, and you know it’s sometimes fun to sit there and think, ‘Oh, I’m going to change the costumes up on them and see how they react.' I love the fan community, I’ve been a part of it before I was even working at LucasFilms. So, it’s all fun and fair at 'Star Wars.'"

You heard it here first, cosplayers -- you deserve the fun and frustration of having to update your fabulous costumes, because you're the best.