I don't think it is odd at all. I would never agree to take a polygraph test, for any reason. There is no way of knowing how that might come out. Even if I'm innocent, the polygraph test could backfire on me and raise more suspicions. I would not even be as cooperative as he was. If it was me I would have told them to feel free to search out in the open, and to get a search warrent for anything else. Once you let the cops start questioning you or searching, it just goes on and on, until you finally put a stop to it.