It should drown out your playing when the volume is wide open. Obviously joking, but yes I've experienced that as well when I was doing some studio recording. It actually bled through one of the mics. In my case, it did quiet down after awhile and became a non-issue.
At the far end of the spectrum and probably only the most severe cases, a grumbly sound is a whole other issue. An automotive stethoscope, awl, or screwdriver tip placed on a stationary piece of the fan, or near the fan while it's spinning would amplify an awful sound if the bearings were going out. Very highly unlikely that's the case with such a new amp, but always something to keep in mind.