I'm bumping this one up. The general who completed the third crusade in this campaign - Esteban the Chivalrous - was only 3 turns from his coming of age when he captured Jerusalem, meaning he displayed as 17 years old. I'm playing 1 year per turn, and he's 30 now. Even assuming he just turned 30 this past turn, 25 turns (years) have passed since the completion of the crusade, and the glory bonus is still 15% empire wide.

Let's keep an eye on this one if you guys can remember it. I'm really wondering if this is permanent, temporary but long duration, tied to the victorious general's life, or perhaps temporary but duration increases the more you earn.