I read in Variety that he is going to be appearing on stage during the summer, but it sounded like that was still a month or so away. I am not particularly good with faces -- actually I have at least mild "face blindness" -- but a dancer who I thought looked like him appeared in the opening number. Then I didn't see him again -- at least I don't think I did. Was anyone else on these boards there last night?
According to this article, he hasn't joined the show yet - but will be joining on July 24th along with Audra's temporary replacement. Unless that date has changed, I don't think you saw him last night.
Producers also announced that Rhiannon Giddens, the musician who released solo album “Tomorrow Is My Turn” last year, will fill in for McDonald during her leave of absence, which will now begin July 24 and extend into the fall. Glover, who’ll join the cast as a featured dancer, will appear in the show during the same timeframe.