Not sure if we are talking about the same thing, but I have a friend who keeps his rifles stored in an air-conditioned room. When he came out to shoot on a hot humid day, his whole rifle was covered in a layer of condensation...it must have been inside the barrel because there was a mist cloud the first time he fired. The rifle was a springer rifle, and it did shoot kinda funny for a couple of shots. After a few shots the condensation evaporated and the rifle was back to shooting in it's normal manner.
Now, if he knows he's shooting the next day, he'll leave his rifle in the garage overnight so it can acclimate.
Not sure if the same inaccuracies would occur with a PCP rifle as it did with the springer.
How did your barrel get wet?
Mike