But when she and their four children were ushered into foul ground up the first-base line in the middle of the fifth inning Monday afternoon, Robin was sure something was going on.
As the five members of the Sims family watched, the giant video board in center field played a short message from David. He said he just wanted to say hi.
"I love you, I miss you," he said.
And then, as the Cardinals infielders took ground balls and right-hander Lance Lynn threw his warmup pitches, David wrapped it up.
"I can't wait to be with you again," he said. "In fact, wait one minute."
And then Sims emerged from the Braves' dugout and his family was running to him. His son, Dustin, 12, reached him first and everything quickly became one group hug and kiss.
"I almost fainted when he came," Roman, 11, said. "I almost had a heart attack. I was looking around like, 'What's going on?'"
Sims, who has been in the Air Force for 14 years, had been stationed for six months in Afghanistan with the Air Force for the last six months. It was his second overseas deployment in the last four years.
After his first deployment, which lasted a year, he also gave his family a surprise homecoming. When he found out he would return to the states a couple weeks early in December 2009, he arranged for his friends in his motorcycle club to pick him up from the airport. When they got close to his house, Sims got inside a big box, wrapped like a Christmas present.
There was no box or motorcycle club Monday at Turner Field, just 42,426 fans, who gave the Sims family a standing ovation when they first came onto the field and an even larger one when David appeared.
Robin was overjoyed by her husband's return Monday. It was a surprise and, yet, it wasn't. She did have that hunch.
"I thought he would be here," she said.
And after six long months, he was.
Teddy Cahill is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.