I think doing the whole Punk is resentful of Bryan angle for Wrestlemania might seem rushed.
In my fantasy booking universe, I'd have Bryan win the title at EC, beat HHH at Mania to further establish himself, then have a longer title reign until somewhere down the line, Punk returns and they go w/ the whole resentment angle with Punk as the a-hole heel.
The old school fantasy booker in me says they should ignite the resent angle this way: Book champion Bryan in a program against Batista after Bryan's big win over HHH at Mania. Once that runs it course, bring Triple-H back into the picture for another attempt to push Bryan back down the card, which would lead to Punk returning to stand up for his friend. Book Bryan/Punk vs. HHH/Batista at Summer Slam (or whenever it's appropriate). After Bryan endures a long FIP segment, when he goes to hot-tag Punk, Punk turns on him and the resentment angle kicks off.