Is it possible you didn't have it snapped completely into the groove? How bad does the cylinder look? There was something else in the water too... and it was distilled water I hope 
Seen bikes suffer corrosion issues very quickly when friends were too cheap to buy distilled.
I'm sure that's what it was...it's just a first for me. That was WaterWetter(the pink) and distilled water...mixed with the crankcase oil...mmm milkshake.
