Check the banjo bolts on the backside of the fuel filter housing. Mine were a little loose and slightly leaking.

 

Did yours leak when the engine was off? Mine only leaks when the engine is running.

 

Only when it was running, was pressurized by the in-tank lift pump. I'd find a tiny puddle of diesel on the garage floor. Slight drip from the fuel lines below the driver's-side footwell. The fuel originated from the lose banjo bolts on the back of the fuel filter housing. Might not be your problem, but really easy to check.

 

Wow, I just did mine yesterday! I drove for about 5 miles, stopped to punch in a gate code at a friends house and smelled diesel in a big way. Pulled up and opened the hood, major smoke! Hosed it off with parts cleaner then found the leak after it cooled down. Started it at sprayed everywhere!! Probably would have burned down if I was on the freeway!
2004 1/2 2500 with 94k miles.
The only other real problem I've ever had with the lift pump that they updated with an in-tank pump after a big fight and a lot of calls!

 

Luckily, mine was only a slightly loose fitting at the injector tube end. Although I don't need it right now, I've got my #4 replacement and I keep it in the truck along with a short 3/4" open ended wrench (although I think 19mm is the correct size).