Unfortunately Gale has had to pull out of his scheduled appearance at the "Windows On The World" reading that is due to take place on Monday 12th September.

Thanks to Evangelium8 on IMDb for the update:

"I've been in touch w/the Blank Theater and he's definitely pulled out because of a scheduling conflict."

Source

According to Guy Norman Bee, director of episode 6 of TSC, Gale will be filming on Monday