We have a Flood Control Team? Whoa. This is more serious than I thought. Thank god I always wear my scuba gear whenever I post.

No I don't think Harry acted more self-important at the beginning of Book 5. I do think his anxiety level was high. This was Dumbledore's fault. He instructed everyone to tell Harry nothing when they wrote in case their letters were intercepted. Dumbledore himself could have found a way to communicate with Harry securely but he chose not to. Dumbledore admitted it was a mistake keeping Harry in the dark.

And if you look at it from Harry's viewpoint, he had ended the school year battling Voldemort and dragging Cedric's dead body through a portkey. Just when he's convinced that Voldemort plans to destroy the earth, he's dumped back at the Dursley's, crawling around in the bushes listening to muggle nightly news. Not a peep from the magic world. Harry felt totally abandoned. I think I'd be a little irritable too.