I've got a few that are protective for a week or two.  No big deal.  I've had a few Mexican standoff's with new mama's over tagging the newborn.  Me and the stick always win.  As long as they settle down in a week or two I don't get excited.  If figure those are the ones that keep the coyotes at bay when we haul them out to pasture.

The ones that think they are Super Cow meaning they can leap tall corrals and fences in a single bound, those are gone.  Rarely have trouble with those though.