When my truck is cold it has a ticking noice when I bring the engine off idle. Like at 1100rpm. It doesn't do it when idleing and and at about 1500rpm its gone. It also stops doing it when the truck has be driven for a few minutes and is fully warmed up. It does it mostly when I take off in first gear from a stop. Ive narrowed it down to the engine since it does it when the tranny is in neutral or in gear and taking off. Is it just my valves/cam/lifters being cold or is there a possible problem?

I have a 2006 f150, 4.2, and a 5 speed manual. The truck has just over 14,000 miles on it.