Thanks. I'm not sure if the purpose was to notify me or if it was as a final verification just to make sure that our interests were aligned and that I was interested in attending. He discussed his research interests and I did mine as well and where they overlapped, and he gauged my interest in attending UMich. It was only at the end that he said that he was confident that I'd be getting an offer later this week.
In any case, he said that they were looking over applications now, so I'm guessing most offers should go out later this week or next. I also get the impression that they do admit people without interviews, since there seem to be a few admits on the results board from this year and last that don't mention interviews.