I noticed this, but not at first I was in the heat of battle.
Me and another race were fighting over two planets, and I captured it using MINI-SOLDIERS. I noticed the class of the planet went to 12 from 9. He took the planet back the next turn. The planet went from 12 to 24. I took it back the following turn with MINI-SOLDIERS again. 24 to 48. By the time we were done. I had 2 planets that were class 79!!! The whole planet I could build on! Granted, I am not opposed to this, but it was amazing to watch. I had to reinforce the planet to save it from becoming 100 or higher.
Has anyone else noticed this? I can provide screenshots if needed for the Devs. Two planets that are over Class 60 are a bit...extreme?