If it was the original fuel filter head, then yes, the primer probably didn't work well (or at all) and the o-rings are usually shot, and some of them develop cracks. A new one was certainly needed. The electrical connector is for a fuel heater in the filter head. It's already broken? The filter heads are known to leak there, too.
These trucks are getting old. The fuel is sucked all the way from the tank, through the filter head and filter, and to the CP3 pump. There are several sections of soft lines which start leaking (air in, not fuel out). The metal lines are also known to corrode and start leaking (my brother's 2003 corroded from the inside out).
Considered a cover-up band-aid by some, one solution is to add a lift pump as close to the fuel tank as possible. For diagnostic work, some rig up a cap with a nipple so they can gently pressurize the fuel tank (like up to 5 lbs.) and check for leaks. Some shove a shop vac and blow air into the tank.
Some have had problems with fuel filters with plastic housings. I always recommend Racor.
And of course, you could have other problems, but an air-tight fuel supply is definitely required.
2004.5 Silverado 3500 SRW 4x4, D/A (LLY), Ext. Cab, Long Bed
engineer837 aux rad, TxC CAI, LBZ MP, Scangauge II, Nicktane aux filter head, KD lift pump, 2008 PS pump, 2011 hydroboost, Frederico Swaybars, Rancho 9000XL, Torklift StableLoads, BFG AT/KO2, Lance 835 Camper often in the bed.