Xbox 360 Slim noise on startup?

I've had my slim (250GB) for several weeks now. During this time, I haven't had any issues with strange noises. Today, after I (carefully) moved the console around and plugged it into a new TV, I heard a strange noise on startup. It's best described as a "crackling" noise, resembling a vacuum cleaner picking up sand. It lasted for only a second, and I haven't heard any noises since. I have turned the console on/off several times since with no further issues, and everything seems to be working fine. Should I be concerned about this noise? Is it likely to be an indicator of a larger problem or just an isolated fluke? My Xbox is under warranty (and will be for 3 years), but I've already transferred/downloaded licenses and content to it, so I'd like to avoid just taking it back if possible.