The answers to both questions are yes. It *can* happen under "normal" conditions at spikes, but it can also *absolutely* be signaling future regulator failure. On rare occasions it can signal intermittent or periodic stator failure, battery cell plates shorting (if you have that type of battery), and occasional other oddities, but I'd put a regulator in it as preventative medicine, and 9 times out of 10, that'll make Bob end up being the uncle you didn't know you had.
