I discovered this tonight...someone else might work like I do. I've reported to Kaytat (the software maker).
So...I leave my stoker on all the time in a rubbermaid box next to my BGE. I set the target temp very low...maybe 5 degrees F. I know it's not gonna get that cold here.
So...tonight...and looking at my temperature graphs, I noticed that every time the sensor went below freezing, the fan would turn on.
I believe this is a problem with dropping the sign on a negative target temperature that has been converted from F to C.
Just a heads up.