I agree with Brendan M (for stainless lines in particular and for regular lines). You can and should torque down on the fittings. Also try tightening and then loosening and then retightening the fittings. That will seat the double flange to the correct angle.
These are the instructions given to me by In-Line Tubes for all new stainless lines on my '54 Suburban. They all leaked at first and then they all sealed after following the above procedure (the one on the Master Cylinder was the hardest to deal with - I still get a drop or two leaking out over a month's time).
