Help understanding leave a little bit

okay so I'm a wife of a e3 in IT school, he has approved leave for the 20th of December to January 6th, already approved, set in stone. We plan on driving to Texas ( 9 ish hour drive from his base. ) And made that known in leave + a plane trip to NC during. Well today we find out he has class on Friday supposedly, the 20th when we're set to leave and he has approved leave. he also has a test that day, how would this work? is he still able to leave as approved or will he be in trouble for leaving despite being approved. Any insight helps a lot thank you sm!