Sophia F. answered 07/24/23
Experienced High School Tutor Specializing in English
I am not sure if this is the first time where "Happy Birthday" was specifically sung during the State of the Union Address, but the president has traditionally always brought several notable people to speak and/or to be celebrated, such as with this Holocaust survivor. This is especially the case since this address has always been a public relation tool for the president and is not an actual legal/governmental event (similar to rallies).
I hope this helps :)