I used to be on the GKC forums, and ideas can sometimes grow out of little things. And all sorts of theories can get huge. One of the things I like to do is just sit back for a second and take a less deep read on the situation.
What if Coyote is just jealous that Annie's grown close to Ysengrin? Could it simply be a petty trick against someone who's taking attention away from him? Consider that he's constantly tearing Ys down when Annie and he are around.