This isn't a big issue, but I'm kinda curious as I still have a lot to learn about dog behavior - Every now and then Kevin knocks his food bowl (with food in it) over. He'll walk over to it, sniff it a bit, nudge the bowl a couple of times with his nose (at which point I stop him if I am there), and then will knock the bowl over. I think this tends to happen if he's got a bowl full of just kibble, with no sardine or egg or anything mixed in, and I do think it tends to happen (although maybe this is confirmation bias) after he has recently had a meal where he did get a special treat mixed in with the kibble. Is this behavior as straightforward as it seems - He's seeing a bowl of plain kibble and complaining about it? Or is there some reason a dog might do this?