that's interesting. I made that trip each weekend during that time. Neither I, nor my Polish wife, at the time, had such a permit. We were stopped only at Lubin.
I suppose it was possible and happened all over Poland. After checking your documents and searching your car boot and realising you were not wanted for anticommunist activities, the soldiers or police let you pass.
Closing an eye was so typically Polish, after all. :):):):):):)