Terry, many folks crossing the border or visiting East Berlin back then had strange encounters. Often, we from the West, didn’t think twice about things which were strictly verboten in the East.
When I drove across the border at Check Point Charlie in the 80s, the East German guard asked me to prove the car I was driving was mine. Initially, I didn’t understand that he wanted to see the registration (since he didn’t ask for that). I must have given him a stupid, blank look or didn’t reply quickly enough – he guided me off to a side and his comrades inspected the entire car very closely! I learned how to remove the rear seat cushion!
I felt very relieved to cross back to the West.