needsUpdate = ([1,1] != "");
for (y = 2; y <= Bottom && !needsUpdate; y++) {
  if ([1,y] != y - 1) {
    needsUpdate = true;
  }
}

if (needsUpdate) {
  InsertCol(1);
  for (y = 2; y <= Bottom; y++) {
    [1,y] = y - 1;
  }
}