Looking at nowhammies10's comparison shots, they seem to be pushing the graphics to the bottom edge of title safety, but still protecting for 4:3. My guess is they didn't want to go too crazy adjusting shots, so they went with a slight graphics adjustment.
If there's anyone still watching the show on a tube TV, there's a high chance the standard definition feed is letterboxed. Or if they're my wife's grandparents, they're watching the SD feed zoomed in so the sides are cut off. Really, my guess for why they're still protecting for 4:3 is because that's the "look" of the show, but the graphics push make me think they'll eventually start filling out more of the screen in the (probably distant) future.