Loud fans, low temperature, uncertain if speed is fine

I have used a desktop HP Pavilion p6000 for about 2 or maybe 3 years now. As far as i remember i haven't done any tinkering inside before, so it still has all of the same things(fan, graphics card, etc.) inside as it did when i purchased it.

This past week my fan has had a loud, steady hum to it. I downloaded speedfan and found that my average fan(i'm pretty sure it's the CPU fan) rpm is around 2800-3000. My temperatures at idle, or near idle with just Chrome up, are between 29c-33c. With a game like Guild Wars up they are mid to low 40s. My cpu usage isn't really ever at an unnaturally high percent, and while browsing Chrome heavily the temperature goes up to maybe 35-40c with maybe 25-40% usage for like a second as the page loads.

The temperature is fine as far as i know, however, i'm concerned about my fans. I've heard often that as a computer ages eventually it will become louder, and just today or yesterday from a so-far-very-reliable-for-ten-years source. The noise is not much of a problem as i can easily drown it out with other noise(even the air conditioner is louder).

I just want to know if i have a safe rpm or if i should really be worried. I've searched google for it this past week but i can't find any definitive help or information for my situation. I'm rather inept at these things, and this has been bothering me a lot lately.

Forgot to mention, but i also did a rather thorough cleaning of the dust inside with an air can. There wasn't that much, but after i did it i noticed my fan rpm increased from normally 2850ish to 2950ish afterwards. The idle speed just sounds like it's too much.