was your moped locked up? if so, someone probably tried to steal the whole thing, and in failing to do so, they didnt want to leave empty-handed.
happened to me once, only instead of stealing my mirror, they cut the gas line and turned the petcock to reserve, letting the liquid gold pour all over the ground. also, they wiped what seemed to be snot or a bunch of loogies over my seat, mirror and handlegrips.
assholes! i hate em all!!!