SNL: HD Easter egg or HD mistake?

Last night, I was watching last week's episode of SNL and I noticed something odd. I know, I am behind on my TV. During the middle of a skit, on the top of the screen I see "1080i 59.94" which we all know is the resolution and field rate that NBC uses. Considering this was in the middle of the screen and not off in the normal HD easter egg area. It leads me to believe this was a mistake. The real question is what happened? Maybe one of our readers in the production industry can fill us in.