Timehop co-founder and former CEO Jonathan Wegener is joining Snap Inc. to work on product design. The move comes just days after Wegener stepped away from the startup he co-founded with Benny Wong in 2011. Now we know why. Recode first reported the news. Timehop is an app that collects past photos and posts from Facebook, Instagram, Twitter and the like and resurfaces them on their anniversary as a fun way for users to reminisce — kind of the opposite of Snapchat’s disappearing messages. The…