The silence was to honour the sport's late doctor, Professor Sid Watkins, who died just under two weeks ago.
Asked about his absence for the tribute, seven time world champion Schumacher told German RTL television: "I have to apologise, as I was still in the toilet.
"My thoughts were with Sid," he added.
Schumacher, whose F1 career stretches all the way back to 1991, said he has "a lot of memories" of British neurosurgeon Watkins, "both on the professional and the personal side".
"When I had my accident in 1999 (at Silverstone), he was immediately at my side," he recalled.