I was wondering if the barking was prior to a bowel movement? Maybe she's telling you "don't watch this is private!"
My dog Shaggy will just start "whining" for no apparent reason. He will just all of sudden stick his nose in the air and let out a whine! I panicked the first few times he did it! I still have no clue on why but he gets a hug just in case it's for love!