how about sometimes putting her in a room where there aren't any books? not that books are bad, on the contrary.
my ds is/was like that from an early age. my dd just started looking at A book, when he would've sat there for hours. on a good note, i've definitely raised a reader! his teacher loves to tell me that she likes his attention span at storyhour, he NEVER has issues sitting still for anything like that, and he's starting to read. so you ARE doing a good thing. just maybe spend certain times a day steering her away from books. :-)