Would you be willing to answer a few brief questions about PlayStation Forums?
Yeah, I was also online last night and didn't get double XP. I was playing on PS4. If I knew earlier I would have gone for the trophy on my PS3 because I thought that the double XP was going to be awarded after the event ends. Unfortunately, this does not seem to be the case.
I played a couple rounds of Wolfpack and shot up to level 18 (PS3), but I've had a hard time getting into the MP for AC4. I really wish the PS3 and PS4 version shared trophy lists and had cross-save capabilities.