Defiant little dog...

So when Ben and I went to Ohio, we left Corky with my parents as we do anytime we go on vacation. The only thing different this time was a new member of their family...a big black lab named Lily. I took Corky over there a few days prior to our leaving to make sure the two dogs got along. Things were great and so I decided that he could spend the weekend (four days total) with my parents. My mom reported nothing but good things about everyone...no problems. When we got home we noticed that Corky would only eat his canned food out of his bowl and not eat his dry food...and certainly wouldn't eat his glucose pill. Right before it's time for dinner though, he always manages to go over and eat his dry food and waits for more. Also, Ben's work schedule has changed so he leaves before me in the mornings and Corky isn't used to that. Ben feeds him before he leaves in the morning and when I come downstairs to leave, I'll sometimes catch him eating his dry food because he has forgotten that I'm still there. Once he sees me, he stops eating, slinks over to the carpet and lays on his side acting very pitiful--hoping and waiting for some attention. At first I was concerned about him, but now I think he's just being a brat. This change in his eating pattern doesn't really affect anyone other than making me worry about him. He is still just as playful as ever and nothing else has changed for him aside from his lack of interest in his food...so I guess I'll just let it be.