Is it possible that the feed changes ever so lightly over the life of the bag. I notice that my dog's food will be much stronger smelling as I open a new bag. The dogs can tell too. They always seem eager to get the first dish of a freshly opened bag. Not so much as the bag nears empty. I can not help to think that the color could change somewhat over the course of a month or so due to the constant humidity changes and the evaporation of the food's moisture content. It might even swell up with high humidity and not quite shrink back down to it's original size leaving the older feed in a larger state.
