Leaf Blowers

I own a 150BT blower that I use mostly around the house for less than an hour at a time. I have noticed that at when I use it for extended amounts of time that at high RPM there is noise the engine makes kind of like a rattle. The blower runs great, starts on the first pull even with the noise it doesn't lose any power. I am just wondering if this is something that I should be concerned about or if anyone has ever noticed the same noise.