I wouldn't stop picking because of it, but at 5 per foot I would definately be trying to figure out where it was coming from.  If it's head loss and you have your deck plates slid in as tight as possible there isn't much you can do in the near term.  Condition of the stalk rolls is something else to look at, but not so easily corrected in the middle of season. 

A corn head is about the most imperfect harvesting attachment I can think of as far as getting all of the crop into the machine.