I was told one time by a company that makes stainless steel brake line kits, that the trick to getting them to seal is to tighten it up, loosen it, tighten it again, back and forth, until the end forms itself to the fitting. This transmission line I think would be very similar, and it would be worth a try. But it sounds like you have it sealed for the moment, so my advice would be don't fix what isn't broke.