Was the rifle cleaned before taking it to the range to fire the 5 shots? Does this happen with every 5 shot string starting with a cold barrel, or the first string you shoot when you get to the range?

If you cleaned the rifle before taking it to the range, I would almost expect the first shot to be a little high- this is normal if you have a light coat of oil in the barrel, the first shot will remove the oil and further shots should be more consistant. This a good reason NOT to clean your rifle after you sight in for deer season- wait until after the season unless the gun gets dropped in water or mud.