Dean sees the raised hand, and he stops trying to grab the man's robes. That's good, that's progress; the dude knows he's here, or at the very least that something's up.

He watches Rodolphus stand there, and then he sees the wand move again. Dean has no idea if what he's trying to do will work, but just in case, he waves, wearing his best :D-face.

When Rodolphus turns, there is perhaps the suggestion of a man's form by the wall, the barest hint of a waved hand.