reid is really gullible so he would've never thought twice about it, and likely would've freaked out halfway through her "making ghost contact" and would've forked over a few extra bucks after he sent her planchette flying somewhere unrecoverable. he was just reid up until about six months ago when he was possessed by an alien life form- now he's essentially an alien that has access to reid's memories. maybe he and ro kept in contact and she was the first to figure out the change?