Edit: figured it out. When you change the mode to TVH and hit continue, you automatically start a new game. Looks like all side-quests and collectibles are reset as well. Sweet 
I was under the impression that you could start a new game of TVHM with an existing character. Is this not the case? I was looking forward to seeing level 50 versions of the main quest rewards 
No only the character that beat NVHM can start TVHM, it’s always been this way in the BL series.
When/If they release the Ultimate Vault Hunter Mode you will have to run it through also on each character.
However, there is an option to reset the missions on TVHM, which should, I believe, allow you to run your level 50 back through the missions for level 50 rewards.
Oh that would be fantastic. I’m gonna dig through the menus, hopefully this is the case.