I understand that him calling himself "Ben" to her means that she didn't realize he was Obi Wan, but I also think it was stupid that she wouldn't recognize him when she's asking for his help between 8-10 years later (even if he did age 30 years in that time).
Also, I don't know why, but Hollywood has an obsession with making kids talk like they're adults. No 10-year-old in the world has ever spoken like she does (that was one good thing about Jake Lloyd's performance, you never forgot he was a child), and it takes me right out of the show when you have a 10 -year-old sounding like she's 20.