Is rapid growth detrimental to a country's Age? In two of the three games I managed to add large tracts of land to the Eastern Roman Empire (four provinces in one game, six in another) and in the last game I added one or two provinces.
Could it be the revolts? I sometimes forget to visit each revolting province to revert them back to my rule. In one particular case I had a province go something like six years before I noticed it.
Or am I simply reading too much into the age level? Maybe this rapid aging is offset by something later in the game that reduces aging - sort of like an Imperial Botox Stratagem.

thanks,
Byron
ps. I've also noticed a small problem with churches and cathedrals. The rules say that you must have a church present to build a cathedral, but this is actually reversed in the game. You can only build a cathedral if you don't have a church.