Really? Do you guys have indoor cats? When my guy has been forced to use the litter box (when he's been sick) he always covers. I thought it was really instinctual. I wonder if maybe if they're indoor cats they don't feel the need for the security re. smells?
My cat, Tuvvy, is loving this weather. He doesn't even sleep with me now, prefers a little patch of dead grass under the rosemary bush. Stays out 24/7, treats this place like a hotel. He's a sweetie though.