THIS is handlebar corrosion. people don't realize how corrosive sweat really is. i was doing an overhaul last year on a buddy's race bike and this was the bar underneath the tape. tape was in perfect shape, but his sweat had gotten inside and literally corroded a hole in the bars. super scary. it took less than a year for this to happen. if you're running bartape, i suggest re-wrapping every 6mos just to check for damage.