I am playing my first BTS game (noble, random standard sized map, normal time) and just stared a golden age with one great prophet very early in the game. Is this new to BTS, a glitch of some sort, or my just not realizing you could do this before???

New to BtS. There are other changes to golden ages as well such as +100% great person rate and anarchy-free civic changes. Check the Civilopedia under "Beyond the Sword Concepts" for more information.

stupid instruction book should have had this, I like the idea of cutting down trees for my information!!!

New change... and it rocks! Also the doubling of GPP while in a GA.

Between those 2, I've leveraged some real use out of them.

Need to try this with a philo leader and try to snag the mausoleum (for 50% longer GA duration).

Nobody wanted to build the Great Wall in my last game, so I did. A Great Spy popped out and I was gonna GA him... but instead, I merged him with my capital and haven't spend a cent on spy % ever since. I'll probably have to increase it to 10% eventually, but not for a while. :)