He is acting totally normal otherwise. It doesn't seem to bother him at all.
It could be coming from so many things. He is obsessed with water and does drink in the dogs' water bowl. I also caught him eating one of the dog's keeble one time. As for his food, he eats Nature's Variety instinct.
My cat will do this occasionally; it's usually stress related for him. I will usually just mix some of his dry food with a little bit of bland rice and chicken for several days and it seems to help.
I wouldn't think the dogs' food and water would cause any issues though.