Please understand that I have no experience with Guinea Eggs. That being said, I would expect that the rule of air cell enlarging & moisture evaporation still applies.
I was late to your party, so glad you caught yours in time! My LG said 100.5 (I think that's what it said-- whatever it was, it was acceptable). Both of my extra thermometers were blazing at 112 &114. I freaked. Lost all.
It was 2 years ago and that's when I bought a second Brinsea.