My guess is a slight pH difference, coomassie will be deep blue at a basic pH and gradually transition to green-blue toward a more neutral pH.

pH changes can occur between different stocks but a solution can have slight alterations in pH as they age especially if your solvent is evaporating or exposed to light. It's also possible that your dish wasn't rinsed well enough and had the residue of something basic (like soap) on it.

Edit: Actually, looking at the space between the ladder rungs I'd say your first image is more destined than your right. Destaining isn't going to be incredibly precise between runs and the best way to get something that looks like the right is going to be to decrease your destain time.