well I have always kept the possibility that Tobi is Obito in mind. you would even find it obvious if you both read the manga and watch the anime at the same time
I stopped watching the anime after the second filler arc because it got too tedious and then began watching after the Itachi/Sasuke fight again. Unfortunately I wasn't able to see it, so when he was revealed i flipped my shit.
Obito's story was shown in the anime pretty late compared to the manga in the manga it was before the shippuden arc which mean just before Obito first appearance in the anime the story was shown later when the mangaka needed to make us remember who is Obito so he can use him again