Uhmmmm....its good to be a landscape photographer
I hear ya, I never had a case where I painted a building, took some pictures, only to find out that the building moved to a different part of town for another photographer to take more pictures.
I guess I side with many others where this isn't really an ethical issue, as long as a contract wasn't breached. Once the model walks away from the gig, you no longer hold any rights over her or what she has on her, unless you have an agreement. This means she is free to do whatever at that point. It would be different if the other photographer showed up at your studio or shoot location and started to take pictures after the MU was applied.
If you feel you own the makeup job and it was just for the shoot, I agree, it would have been wise to have her wash it off, but that should have been made clear at the beginning.