I wouldn't worry too much, if she's not mithering you for her breakfast, then she's obviously not hungry! As long as she eats it when you get back from your walk then that's fine, and if her walk is later than normal and she's still not bothered then you don't need to be! You don't say how old she is - perhaps she's just letting you know that it's time you dropped one of her meals.
As long as she's not underweight then you should consider yourself lucky that you haven't got a 'typical' cocker, who wants to eat all the time!
