Maybe I'm the only one who's had this problem, but sometimes I accidentally attune an animal when I forget to unequip the flute (from attuning a different animal prior). I think it would be useful to be able to cancel attuning an animal (by pressing esc or something), and it not affect your flute usage, but obviously also not increase trust level with the animal.
It's not a huge deal, just minorly inconvenient to have to carry out the whole attune song when you didn't intend to.