Finally got a chance to shoot my new XD-40 sub. I had some Tru Glo night sights put on it. I really love those sights. Anyway, I shot about 100 rounds thru it and the front sight was loose. I could move it side to side. When I got the gun home (probably 6 hours later) I notice the sight wouldnt move at all? Whats the deal? Did heating up the XD make the sight move? I had the local shop put them on and will be taking it back but just curious what happened.