I have not contacted them about the problem, didn't expect much of an answer from them.
I have sprayed the fittings with brake cleaner, and the leak comes from between the nut and the line. Therefore it seems the flare is not seating. I have re-tightened as much as I dare, without cracking the brass fittings.
Do you think maybe screw the line fitting all way off, and put a light coat of grease on the nut where it seats on the flare, and re-tighten?