It was cold out this morning, like 10 below zero. Not super cold, but enough to notice.

My truck wasn't plugged in, nor should it need to have been.
Started as normal
ran for about 5 seconds (sounded cold, but again it was normal
then it stopped running.
It woke up, noticed it was cold, then put its head back under the covers and said "not today". Just like Garfield.

Repeated attempts at starting have been met with turning over but no fire.
I noticed a small leak at the fuel filter where a 12 gauge wire plugs into the top, only appears after priming.
Cranking is slow. I checked the battery terminals and tightened up the (+) terminal on the front driver's side battery.
It has been plugged in now for about 3 hours but still no joy.
Yesterday, I noticed that it took an extra second or 2 of cranking to start it up when it was warm.

Ideas? My first thought was gelled fuel but I've literally never had a problem with that. Ever. I use additive on every tank and the fuel stations around here are obviously in tune with the local weather conditions. That plus the liquid coming from the filter mount says the fuel isn't the problem.

Air?