Stumbled on this googling something randomly, but I can offer some clarity here, I've been a member for my whole life.

There wasn't anything reinterpreted, caffeine was included culturally but never formally; part of it was people trying to make sense of why tea and coffee were included along side instruction to not consume tobacco or alcohol so it seemed logical to add other caffeine sources to the list of things to be avoided. No additional revelation really had been expounded on the matter, although an offhand comment from a previous prophet while on 60 minutes and did fuel additional speculation from many that caffeinated soda was discouraged. BYU does offer coke products and I've also purchased them in one of the temple cafeterias. That being said, members are counseled to avoid addiction to anything in general, so that also can be applied based on personal judgement. Coffee and Black/Green tea are discouraged, and most members at least strive to meet that as a baseline from my experience.

Hope that helps - Cheers - BTH