I noticed that some shows did the same thing, too. I believe Something Rotten, Gentleman's Guide, Hamilton, and other shows have evening performances added on Sunday because of Columbus Day.
It occasionally changes close to the dates... but usually months in advance.
For example, I was just looking at the Kinky Boots calendar and it has a diff schedule for the winter months already set. It's posted on their website. It has a diff schedule for Jan-Mar and then changes again for the spring.
I was SURE I saw Beth Malone in the audience of An American in Paris last night, but I thought I must just be seeing things! Glad to know I'm not crazy and that actually might have been her.