Daisy and Delilah have a few "Mexican Standoffs" now and again when food or space is involved. They growl under the cover at bedtime at each other if one of them is in the way of the other. Sometimes, I see them giving each other a toothy grin and I just firmly tell them to stop. If I don't remain calm, they get worse. They're also still trying to figure out which one of them is top dog