thanks again guys for the replies. I kind of thought it might be some kind of harmonic resonance at that RPM, but wanted to make sure. There isn't any power loss, or anything, just this brief, fleeting minor annoyance- I can easily overlook. I just avoid cruising at 3000 RPM and all is wonderful!
(6,800 miles)
Rain and clouds forecasted all week!!! Daayum!!!