Since installing Leopard, fans on constantly.

I installed Leopard this morning, and I have all of the updates on my MB like I'm supposed to. I've done nothing more intensive than running FF and playing around with the system (nothing like Transmission or burning discs or anything), but the fans have been on constantly. I shut down the system this afternoon thinking that it just needed to cool after the installation, but the fans have been on for the last hour or so while my wife was on here.

Is this a common problem, or should I start getting worried? Thanks for any info!

The fans were running at about 6200 RPM with no downtime. I'm on the same machine right now with a fresh restart, and everything's quiet, so maybe the machine was just working some kinks out. I don't know. Thanks for the reply, though!