True, she appeared at other functions in other Star Wars tees, so it might be all just a promotional stunt for Fanboys. But I ask you: Do you care? Because I don't. It just means she's got a couple of Star Wars shirts at the bottom of her closet. No different than you or I, I'm sure.
According to an interview with EW, Kristen says:
"I love nerds. Comic-Con junkies are the tastemakers of tomorrow. Isn't that funny? The tables have turned. They're a fiercely intelligent audience, which makes filmmakers want to please them. But I'm looking for the fangirl to come out of her shell a little, to be more accepted."
Hello, Kristen! :::waves::: We're right here, waiting to be adored.