A mechanic at my local shop told me my pannier was dragging, I never noticed
Been riding with the same panniers for like 3 years. Last Tuesday I stopped for air and the guy working there pointed at my rear wheel and said "your bag's rubbing the tire, that's why your frame's got that wear mark." I looked down and sure enough, the hook had slipped down a notch. Fixed it in 10 seconds. Now I check that every morning before I leave. Anyone else had a bike shop catch something dumb you missed for months?
I read somewhere that pannier hooks can slip from road vibration over time, so it's actually pretty common once they get worn. Good on that mechanic for catching it, mine only ever notice my tire pressure is low.