Watson, playing in her first tournament since a debilitating bout of glandular fever, appeared to have all the momentum at the start of the deciding set, having reeled off four successive games.
But Voegle’s unscheduled interval prompted world No48 Watson to drop serve and the 21-year-old could not recover, losing the rain-delayed first-round match 6-4, 2-6, 6-4.
“Maybe she did need to go, but I should have been focused and ready for whatever,” she said, when asked whether she felt Voegle’s break had been a deliberate tactical ploy.
“I think some girls definitely do that. They want to take a break and gather themselves as well and maybe try and slow their opponent’s rhythm. What can you do? You’ll never know.”
Watson had hoped to improve on her last two appearances at Roland Garros, when she progressed through qualifying to reach the second round.
“I thought I had a good draw and a good chance to get through,” she added. “I knew it was going to be tough, my first match back, but still I’m super disappointed.”
British women’s No1 Laura Robson, meanwhile, was forced to withdraw from the doubles draw on doctors’ orders after suffering back pain.
Men’s second seed Roger Federer dropped just four games in an 82-minute thrashing of India’s Somdev Devvarman, while unseeded home hope Gael Monfils followed his shock win over Tomas Berdych with a second-round defeat of Ernests Gulbis.
Women’s top seed Serena Williams overwhelmed French youngster Carline Garcia, while there were also routine victories for third seed Victoria Azarenka and fourth seed Agnieszka Radwanska.