Basically, without changing the fittings on the Fuel Pump, it's something you're going to have to put up with, if it continues to come back at a later date.
If you're not wanting to change the fittings, (again if it comes back, which it likely will not do now that you found a leak) there are a couple of more options.
1. and this is the easiest, and the method I chose when i experienced the same thing
Fill your fuel tank with some BioDiesel, if available, B20 will swell the various o-rings in the system slightly( therby helping to seal up any places where air is being sucked), it will also totally clean your fuel system, from the tank to the injector tips, lubricate your injectors better than anything else, and also, as soon as that biodiesel hits the injectors after you fill up, the truck will change, run smoother, quieter, and overall better.
All those good things do come at a price, specifically your fuel filter..... After running that tank of biodiesel, your fuel filter will likely be nastier than you've ever seen it, it's best to check it after you fill up with normal diesel after that tank of bio.
You may find that, the benefits of biodiesel outweigh the extra few cents per gallon you may pay for it, however...
#2.. If you don't mind putting up with a holy mess if you ever have to replace the fuel pump, you can apply some silicone sealant(resistant to fuels of course) onto that fitting on the inlet side of the fuel pump to seal it up.