Usally you do have to record the internal temp, this is to make certain that 
the digital read-out is working properly, Blood banks are required to do 
this, and to my reccollection the guidelines do not seperate types of labs 
for temps,I am sure if that is in-correct I will find out. But even so an led 
read out can get stuck or malfunction and I have seen discrepancies between 
the top shelf and bottom shelves in large refrigerators as well as a 2 degree 
variance in an LED versus an internal thermometer
in glycerol.                             Dana