Hello Jacob, I didn't paint mine, and it definitely has something to do with temperature. I first noticed that when I had kept the model in an air-conditioned room, the rigging loosened. Later, after I had moved it to a warmer room, the line grew taut again. I have seen the same thing happen several times since then. On several colder nights it became loose, and later, when the sun came up and warmed the house, it tightened once more. I was wondering if somehow sealing the string I used, while it is taut, will keep it from loosening again? If anyone has any ideas I'd appreciate hearing them. 

 Al