Dell Inspiron 1545 loud fan

I just received my new Dell Inspiron 1545 laptop. I love it except that randomly (maybe every 5 mins or so) the fan will turn on. Right when the fan turns on it is relatively loud and then gets quieter as it keeps running. The fan will then run at an audible volume for 30 secs to a minute or so and then turn off.

Has anyone else experienced this with this laptop? Just wondering if this is normal or not.