I just picked up a Herpstat II and think there might be a problem. I have 2 identical racks right next to each other set at 91F. One is reading 88.4F and the other is at 106F. Both zones were set correctly as far as I can tell, and both temps were confirmed with a laser temp gun. I have disabled the unit for obvious reasons until I hear back from either Spyder or my rep. Any troubleshooting ideas are welcome.