Elphaba3, I've seen the show plenty of times and that was the first time an actor has gone off stage left, I don't think it's part of the show. Especially since Block got a little nervous looking and made some noises until he ran back across.
Also, just for the record, Annaleigh and Stephanie are amazing. One of my favorite (If not favorite) pairings.
Well, I'm glad he got away with it.