Could'a cooked it. Used to get them in from the local Manheim auction all the time after the old guys who could barely drive sticks worked to clutches to death on the way into the auction bays. Some of the V8s would simply explode the plates.
Just get out of the city and drive it normally for a while and see if it clears up. Didn't smell anything, did you? I doubt moisture had anything to do with it. Driving in the rain would be worse if that were the case. Mileage, yes. Humidity, no. Oil leaks at the rear main seal can also cause a problem, and the M20 engine is known to leak from nearly anywhere it can.