Even though you were older than her, you were still in the innocent phase. Being a young prepubescent boy means you are naturally curious about the opposite sex. This is a common story, but a good one, because I was worried as I read that you would be touching her, which you did not. It's normal for young kids to be looking at each other's bodies, compare and contrast. The reason why she asked you to look is likely because she was discovering her body herself. I remember being at my grandparents house with a big mirror closet and I would take off my pants and stretch myself out so I can look at my lady parts.

What you did was merely innocent. Neither of you had any idea on the concept of sex, and you did not violate her in any way. It's normal to want to look at each other.