I have noticed that when I start my truck after it has set (Over night or longer)
that it gives a small puff of white smoke on start up. It starts fine. It does sit for long periods of time though. After it has been started once it is fine for the rest of the day. Is it just cold weather?

unspent fuel in a cold cylinder that depends on heat detonation.

The small puff of gray/white smoke at start up is absolutely normal for a cold diesel engine in cold weather....

that is what i though but just wanted to make shure!