Why do cables need break-in?


I just had the experience of having newly introduced speaker cables (AudioQuest AQ-8 bi-wire) break in. When I put them in a few days ago they sounded thin, bright and lacking in bass. Now, after 4 days and 40 - 50 hours, they sound far better: relatively neutral frequency spectrum with much more bass weight. I'm delighted, of course, but I'd like to know why this happens. Will I experience the same scenario when I change interconnects?
pendragn
My thanks to 2001impala, Sugarbrie, and Audiopath for their explanations and for taking time out to provide them. As for you other guys, try this: My wife and I have a wonderful marriage. It's probably because we go out twice a week. She goes out Tuesday, I go out Friday. (<--courtesy of Henny Youngman):}
Could someone please produce some sources for this? Like, not from people selling cables.
I suppose, you are very well aware of the fact, that there is no really convincing scientific explanation for this.
Our ears tell us though, that this phenomenon exists. So if you " believe " in science, you'll say that the ears are wrong and if you believe in what you are hearing, you'll say that science falls short of the fact and cannot explain it. P l e a se lets not start this argument again, because it leads nowhere!