Cold start...too much smoke?

[oneday1]

So I've searched the forum with not too much luck to try and find an answer to my question so I'll go ahead and ask.

When I start my truck after sitting overnight it will start and run fine but after about 30 seconds it starts pumping a good deal of smoke out of the tailpipe. I'm thinking when it warms up enough to activate the choke? The smoke increases for a bit and then after about 5 minutes will stop.

Video here: http://youtu.be/r_3oWINPMY0

Can run the truck all day and never see that amount again even if stopped for an hour or so. Only happens on cold starts. And cold is relative, doesn't get much below 40 here. This is a fairly recent development and although I have done a few things to the truck (full fluid changes, rebuilt carb, normal tune up stuff) I haven't opened up or worked on the engine at all. I do believe it's running a little rich but would that be the cause? No emissions control stuff on this truck at all if that is important. It doesn't seem like a huge deal but since it's a recent development I don't want to miss something big that might be waiting to fail. Thanks in advance for the help!