>>/54930/
Maybe "unsymmetrical" tightening of the two bolts?
I mean, frequent shifting between tightening both bolts to the final 12-14Nm.
Or maybe the switch from riding outside in ciclismo weather to winter hell?
Frame carbon, bb shell aluminium, spindle steel, crank arm aluminium, crank arm bolts steel, tension cap plastic...
Things just get some play with this mix of materials.