Vettel is out very late, so doing a slower lap and finding time might not be an option for him, so potentially other cars will save the tyres a bit better and find a better gap.
edit:- I think judging from everyones time the track was a tad slower, which is a shame as Hamilton clearly improved. Everyone else was like 2/10ths down including vettel from his split in the middle... meaning Hamilton effectively gained 3/10ths(1 faster and 2 slower track) I think he had the speed but so often drivers really just put their best lap in for the end of Q3, Vettel is one of the only that doesn't generally do that, he just goes balls out.
So, up at 7 tomorrow, if Hamilton doesn't beat Vettel to the first corner I might just go back to sleep.