Ok so I bought a Honda eg6500 generator and I've noticed that after about 20 minutes of running it starts making this rattling/knocking/scraping noise. It's kind of a combination of all three, haven't quite figured out what it is yet. This generator is brand new. I'm not sure why the engine has to run for 20 minutes for it to start making noise? It's done this twice now. It's really not that loud but if you're standing right next to it you can hear it. Basically the overall generator noise covers it up for the most part. So I'm not sure what it is exactly or what I should do. I really don't want the dealer to tear into my brand new generator that only has an hour of run time on it. Any thoughts on what it could be?