I also found maybe a 'glitch' in time....when I set , in my first two tribes, the games speed at fast, there was no problem. Only after that I went to walk my dogs and set the speed to slow. When I turned it on again and changed the speed back to fast, my fire stil said it had +26 hours (!) to go...it's now at 20 hours (paused the game inbetween) and because I'm so far in the game at that tribe (my 1st magic one) I didn't start tat over but with my 1st nature tribe I wasn't that far along and when it happend there I did start over.

Changing the gamespeed back to slow only made the hours go up.
I did not mess with my pc time.
Maybe I did something wrong?