Why does my 3 yr old hold objects rlly close to her face?

my daughter loves books but the way she interacts with her books and toys worries me i don't know if its normal but she can look at the cover of a book for hours and she likes to hold it so close to her face it practically touches her nose and i constantly have to keep telling her to hold it away from your face should i be worried that she does this or is it a normal thing 3 yr olds do?