Quote:
  
 
				Originally Posted by Cocos 
 Почему? Вполне нормально.
 
    Normal is not 
good. ;)  
 Quote:
  
 
				Originally Posted by Yuki 
 It seems OK to say "Она взяла эту книжку из библиотеки."
If so, then why?
 
    "Из библиотеки" is understandable and grammatically correct, but it's not a common way to say it.  
So a deliberate change of preposition in this standard expression attracts attention and even can give an impression that the speaker hints at something (like he/she just "took" the book from the library without permission or something :)).  
I'd advise just to stick with "брал/взял в библиотеке".