Nina and the Children's Bible Synoptic Problem

So my 3 year old, Nina, and I were reading the nativity story from one of her children's Bibles the other day. As I was reading out the closing words "Joseph made a bed for him to lie on and..." she interrupts me. "No Daddy, it was Mary who made Jesus' bed". Nina has a good memory for these types of things, so I suspected she was reclling the story from one of her other children's Bibles. So I checked her Candle Bible for Todddlers, and sure enough, it climaxes the scene with "and Mary made him a bed from the straw". I must admit I felt a little gush of pride at my three year old spotting the small differences in the broadly similar accounts of the same story. She's a smart kid.