That was one crappy run

I will post the Garmin results later tonight, when I can sync at home.  It was supposed to be 3 miles at 4.5 mph on the treadmill on the gym at work.  At 2.35 miles into it, I felt my heart jump into my throat.  Lo and behold, my heart rate was going from zone 5.2, 5.3, 5.4....all the way up to zone 6.0 in a matter of seconds.  I turned the treadmill down to 3.0 mph and walked for about 10 minutes at that point.  I tried to regain composure and jog the last .65 miles, but I could not get my heart rate low enough.  BOOO!!!  I think it's from stress.