Fan occasionally vibrates

I have a G3 3579 and it's about 3 months old. When I first bought it, the fan would only really set off if I opened a lot of tabs or played games. Now it's constantly going and making a kind of "chugging" noise. And on top of that, from time-to-time it sounds like it's spinning fast whilst brushing against something. This causes the keyboard to vibrate. It's happened at least 10 times within the past two weeks. I tried to see if the vibrating would stop on its' own, but it just sounded like it was increasing in speed. The only thing that works is shutting it down and leaving it for at least 10 minutes. Does this mean there's an issue with the fan? What do I do? Edit: the vibrating sometimes starts up if I move the laptop from one position to another. Sometimes, not always.