It says they screen for these three things when deciding a secondary. If you meet these 3, then I wouldn't worry, give it some time or give them a call. But thats a pretty light screen so I'm guessing they're just backed up. I got the July 10th email and got my secondary last week, they seem to be going out slowly.
1. Applicants to the University of Minnesota Medical School-Twin Cities campus must have a 24 or higher on the old MCAT. For the 2016 cycle there is no minimum score for the new MCAT.
2. Applicants must be US citizens or permanent residents.
3. Prerequisites will be reviewed to verify they have been or will be completed at an accredited U.S. or Canadian college or university by July 2016.