question on flexwatt

I just did my rack with flexwatt and a herpestad thermostat, and Im measuring each panel and there are 2 that are heating about 3 degrees below the other two, is these normal? I wired them in parallel but they are not heating equally, any info would be great.
thanks

There often is a difference between the top and bottome shelf which is normal.

How many shelves do you have and where is your probe?

I have 4 shelfs and probe is on the first one
3 shelfs are in parallel, and the other one is separate

I've always heard to put the probe in the middle of your rack. It may be a degree or two off from the top to bottom but it will give you a better average than putting it on top or bottom alone.