what's that noise?

Today, as I was checking my email, facebook, twitter, yada yada yada....I heard a sound that was sort of out of the ordinary. You know when you hear a sound that may have been familiar before, so you sort of block it out until you realize that that sound isn't a sound you should be hearing right then? That's how I was today. I was typing away, or rather, clicking away at the computer, when I realized that this sound that had been white noise wasn't really an expected sound at that moment. It was our TRANE!! Our furnace had finally decided to kick in for some reason. I'm still going to look into it, because I don't think this is the "right" way for our furnace to start up every season, but, for right now, I'm enjoying warm toes.