Is this bad?

My PS3 started to get kind of loud and it started when i was playing the Uncharted 2 demo and got loud after…2 hours of play, is this bad? and what can i do to stop it from getting this loud (3rd gear or 2nd gear)? My PS3 is the MGS4 80g b/c ps3 had it for almost 2 years ….no had it for 2 years lol. I HAVE BEEN CLEANING THE DUST! AND IS WELL VENTILATED!