I visited the border, though not in Berlin, in June of that year.
No one saw what was coming even so soon before, and people were still being shot.
I was with a military group, and within a few minutes vehicles brought more guards who watched us with binoculars.
Our guide warned us not to "show zer arses" which apparantly some vistors did and which brought official complaints from the other side.
It seems now like a different world, which of course it was.