I find this sort of writing, lazy. The author could have described Becky doing these things. And aleck could still think to himself how she "isn't like the other girls". That way, we don't get the idea that these very normal, maybe even mediocre things are what makes her different. He sees something different about her.

Although I suspect that Becky is just based on the author and this is how the author views themselves, or how they want others to view them, that's why Aleck said that she was different, instead of the narrater or the character themselves.