Hard to tell if it is the ages, generation, or both. My 3 sons, 24, 21, 16, also are not really able to talk about 'what if dad....', they even were nervous visiting in hospital, and couldn't sit with me at home until all the bandages, drain, and stuff was removed. Their grades dropped, dropped off sports team, under it all I could tell they were scared. We probably should have used family counseling, but good luck getting them to go.
I would let it go, you might find as they get older, have own kids, they can be open with the feelings. I'm guessing that if you look close can tell how much they love you, which is all that counts. Just give them hugs and you know everything is fine.