Aziraphael is a little slower to anchor Crowley's hips than he probably should be, and while he doesn't actually need air, it's something of a surprise when Crowley's back arches and for a moment he draws back. He manages to pick up where he left off with a minimum of sputtering, however.

His intended mild 'hmph' comes out as a pleased hum, partly because Crowley's reaction was obviously positive and he hasn't quite shaken the conviction, despite all evidence to the contrary, that he is forever doing this wrong.