Actually, I don't think so. I think giving credit to new partying 22 yrs olds who hung in Casey's circle (or she in theirs) for being astute enough to notice Caylee was missing and accepting Casey's word for where she was was kind of mimics what happened with George, Cindy and Lee. It's odd, how these relationships seem so surface in a way. Even her old friends didn't ask enough questions. The only one who did, or started to get a feeling something was awry was Cindy herself.
Casey knows everything there is to know, and she isn't sharing.