Just another thought to consider, it may not only be emotional, but an actual physical situation. Don't get defensive and tell yourself, she doesn't get a lot of sugar, but look at it objectively. Make a food diary of what she eats and then note when the accidents occur.
Watch the sugar intake. Sugar works in a child, like alcohol works in an adult. ( the alcohol converts to sugar) The sugar weakens her muscle, just like a drunk, they lose control of their muscles.
Take a look at her sugar intake. For those more sensitive, it might even be the just a piece of fruit, bread or even pasta which converts. B complex vitaimins help the body turn food into energy . I've worked with bed wetters who when we put them on a BALANCED, COMPLETE B Vitain, and change the diet to less "sugar" foods and the bed wetting stops.
Im not negating the emotional aspect, it is just one more thing to look into.