[Help] Peeing in food bowl?

I adopted Dennis (6 y/o male chihuahua) 3 weeks ago, and have only 2 housebreaking incidents (both urine) since adopting him. This morning, I put out his food, went to unload the dishwasher, and when I came back I saw he had peed in his food bowl with his food still in it. I've never seen this behavior before with my previous dogs, does anyone know what an explanation could be? I've been consistent in his feeding schedule and amount of food since adopting him. via /r/dogs http://ift.tt/2qO5wI6