Why was Defense Secretary Lloyd Austin's hospital stay kept secret for days?

[Blaine91555]

Austin spent FOUR DAYS in the ICU; that's pretty serious for a 'relatively minor' procedure. 

I can only imagine what kept him there for that many hours.

I'm perfectly fine with him having his privacy, but hiding that he was in the hospital is a step too far for someone at his level. Even that might be understandable, but not telling the POTUS is very odd. We don't really need to know to be honest, but the White House certainly does.

I wonder if there is even a policy on that?