rust in ceiling light fixture
Today as I was doing some cleaning I noticed something inside the glass cover of a light fixture. Thinking it was some bugs that needed cleaning I removed the cover only to realize it was small (dusty looking) pieces of rust. I noticed that one of the nuts that holds the fixture to the ceiling also had rust on it. From what I could see it looks as if at some point some water dripped through around the screw and into the glass cover. There are no water stains at all around the fixture.
Almost 4 years ago we had a bad windstorm that caused shingles to come off and water leaks in that bedroom. Since then the roof has been replaced and as far as we know there are no leaks. It's possible that we haven't changed the bulbs in that time since we don't use that fixture very often.
My question is this: Is there anything else that could cause rust? I really don't know if this is a new problem or not, but wanted to make sure we check out any potential problems that could cause this. There is no plumbing or pipes that run over this room.