At the gun show Saturday, a gentleman offered me a Colt revolver. It was a 6 shot .38 Special with a 2" (appx) barrel. It felt very light, on par with a SW 442. I asked him what model it was and he called it a 38 Special.

Is this enough detail to determine the model?

There will be a model number on it you can look up. Sounds like an "Airweight" or "Featherweight"

.38 Special is not a model but Colt made .38 Special 2" guns as Police Positive Special, Detective Special (essentially same as Police Positive Spl).  I think they may have made the Army Special/Official Police as a  2 or 2 1/2 inch gun.  These are all 6 shot revolvers but the AS/OP and later Trooper are built on a larger frame.

Colt made three generations of detective specials the first or second are pretty light and six shots.

Cobra, the alloy framed version of the Detective Special.

Is there a model of these revolvers that has the shrouded ejector and shorter grip?

Starting sometime around the early the 70's, the Detective Special, the Cobra and the Agent all came with the ejector shroud. They should have markings on the barrel to let you know what exact model he has.

1st one is an alloy Agent, 2nd steel Detective Special, 3rd old style Det Special all 6 shooters

The third model Detective Special and the second model Cobra both had the barrel shroud and short grip frame. I don't believe that the Police Positive Special model ever came with a barrel shroud. The Cobra model has just been re-introduced by Colt using a totally new lockwork design, and has the barrel shroud but I am not sure about the grip frame size.

I'm going to have to track this guy down I guess.

I was making the deal on a Smith when this gentleman steps in between me and the promoter of the show. He starts asking about my gun and was told that I had just bought it. He then pulled the Colt out of his pocket and offered it to me. I asked if it was a Detective Special or a Cobra and this is when it got confusing. He called it a Colt Special, not a 38 Special, well I had never heard  of that model.

The finish looked like it was dipped in motor oil. The bluing was as nice as you will find and I really thought it may have been refinished. The grips looked brand new as well. By the time I counted out the cash for the Smith he had wandered off so I never even got the chance to look it over to find the model.

The one that got away.

Tell me about it. I have an even better one that will haunt me forever.

Police Positive did come with a shrouded barrel but only for a couple of years.  I have one.