You asked her what happened. Right, okay, that was a relatively simple question. The answer.. hah. She didn't feel like explaining it. Didn't know how to either.
Okay, it was pretty innocent. She had been riding around the neighbourhood on her bike, just trying to get some fresh air. Superhero or not, she wanted to enjoy the simpler things from time to time. You were likely trying to do the same: she had observed you briefly, just watering the plants in your front garden. Though she wasn't really paying attention to your actions, no, she was paying attention to your looks. That was the issue. Maybe she stared for a little bit too long, and maybe she lost control of her bike, and maybe she crashed face-first into the curb right outside your house. Before she could object, you had Kara on your couch, and were tending to her wounds. Asking questions.
Ah, right. The question. She answered with a forced chuckle, "I guess I just wasn't paying attention." Hey, it wasn't a lie.