There are a lot of "hidden" updates in the MUTCD that was released in May.
One such "hidden" update has now taken away the option of allowing highway shields to exceed the height of the initial uppercase letter in Street Name signs (which is why on the Road Related Illustrations thread, you have not seen the shields in any of the street name signs I created lately exceed the uppercase letter's height), in the original 2009 manual, there was an option for such a thing.