A similar thing happened to a former coworker who was an SOF officer. This fellow and a number of other SOF arrived in a C-12 and touched down at Pope shortly after AF 1 bearing Jimmy Carter arrived. Some of the very large Secret Service contingent securing the air drome surrounded the aircraft and held the SOF personnel at gun point for several minutes and insisted they remove their sidearms before being allowed to go to the flight ops building. There were some irate calls to SOF HQ but they were told to shut up and wait for the Presidential party to clear the air base.
The Secret Service is institutionally paranoid and thinks anyone with a firearm is going to try and assassinate the POTUS.