It's a look that they just have in their eye, very hard to explain. Some horses have a look in their eye that seems to say "I'm going to kill you!" and some have a look that seems to say "I'm so scared I just might buck you off!" She just has this look that says "I'm perfectly happy, reliable mare and I'm not going to hurt you."
That doesn't make any sense but I don't know a better way to describe it. I'm such a dolt...lol