[Hex Terrain]Why is it producing a little gap?

I am not sure why is it producing that little gap on this hexagon generator script.

Provided picture: https://gyazo.com/674e2a451561179a638470f7c16b2145

Provided model: https://www.roblox.com/my/item.aspx?id=932301764

function MakeHexTerrain(dummy, rows, columns, parent)
    local currentRow = 1;
    local currentColumn = 1;
    dummy.Parent = parent;
    local StartPos = dummy.CFrame;
    for Row = currentRow, rows do
        wait();
        local row = dummy:Clone();
        row.BrickColor = BrickColor.new('Really red');
        row.Parent = parent;
        local rowPosition = row.CFrame;
        local rowSize = row.Size;

        row.CFrame = rowPosition * CFrame.new(0, 0, rowSize.Z * Row);
        if Row%2 == 0 then
           row.CFrame = row.CFrame * CFrame.new(row.Size.X/2,0,0) 
        end;
        rowPosition = row.CFrame;

        for Column = currentColumn, columns do
            wait();    
            local column = dummy:Clone();
            column.BrickColor = BrickColor.new('Forest green');
            column.Parent = parent;
            local columnPosition = column.CFrame;
            local columnSize = column.Size;
            column.CFrame = rowPosition * CFrame.new(columnSize.X, 0, 0);
            rowPosition = column.CFrame;
        end;
    end;
end;

MakeHexTerrain(workspace.Hexagon, 10, 10, workspace);

I know the generator is innacurate, but I am unsure on why is it producing a gap like that.