Given my experience as a previous applicant there, knowing how many people they interviewed for the number of spots they have, I kind of doubt this is the case. They interview many more people than spots, so I can't imagine them having so many bad interviews that they have to go back to the uninvited folks in order to fill their spots. My guess would be that they simply haven't gone through all the apps and made all the invite decisions yet. But, I also don't know what info you were given about when you would hear back, or if there are other people who have received invites.
Oh, it's occurring to me that they have two programs. I only interviewed for the Counseling Psych program, so can't speak to the Clinical Psych one.