No idea. My best guess is that Vernon and Dee wanted to surprise Elvis and instructed the household staff not to say anything.
I’m sure one of Elvis’ men would have told Elvis if they were there at the house, but like always, they were all with Elvis in California.
Years ago, we were looking for a place to get married and we looked at the Storz mansion in Omaha. The Storz son still lived there and was very eccentric. He showed us hand carved oak pillars that had grapes and grape leaves. His parents took the family on an around the world trip & the maintenance man had painted all the pillars as well as hand painted frescoes on the walls. They commissioned an Italian artist to come to the US to paint them. When we took our tour, the son was stripping the oak pillars to get back to wood.