Why is my iPod emitting a high pitched noise from the click wheel?

Basically whenever my ipod is up and running, I can hear a high pitched whine/buzzing coming from the click wheel. Ipod works just fine, however i’m just wondering if I should be concerned at all? It gets a bit louder when charging. Haven't noticed any overheating issues when charging so far. Edit: I did take out the original hard drive and installed the iflash solo with a 3000mah battery. I want to say it's coil whine, but idk if that's possible with the iPod.