A few days ago I had to replace both low-beam headlights on my 2006 Mazda 6. The left one burned out, and, as soon as I had replaced that bulb, the right one failed. After replacing both bulbs, I reinstalled the outer cover behind each. This is the black, plastic, domed cap that goes on the back of the headlight assembly. The left-side cap screwed in nice and tight. But the right one is loose. It jiggles a little. Did I miss something in screwing the right cover in?