IGN, when the site interviewed Filoni about the Star Wars Rebels season 2 finale, flat-out asked if Ahsoka did in fact survey her encounter with Vader - something that 'Twilight of the Apprentice' heavily implies without properly "confirming." Here is Filoni's response:
Is that what you saw? That's so interesting. That's so good. You know I think it says a lot about who you are, which is great. You're an optimist, and I think that that's strong, I think that that's strong. [Laughs] It's an interpretation. I mean, the thing for me in this moment in time with this story - and I was pretty clear about this from the beginning in that Rebels is not Ahsoka Tano's story, nor is it Darth Vader's story, and we worked really hard to bring those characters into the story. But ultimately, I have to service Ezra and Kanan, and the crew of the Ghost. So a lot of that episode is portrayed through their eyes, and especially Ezra's, as he witnesses this kind of titanic thing happening.