Yeah, but you have to remember that George is ex-LE and Cindy called LE. George would know not to clean out the car.
What I think happened is that Casey thought Cindy was bluffing about calling LE. And I think after Cindy did call that Casey may have then said something about Caylee being dead or something that made Cindy believe there was that possibility. At that point I think that maybe Cindy and George went into the protect Casey mode. Since they checked the back yard, and it just so happened that the dogs allegedly did hit back there, I think this is what happened. Or it could be that George figured it out, and that he told Cindy and they went into protect mode at that point. IMO