Simpson, 32 and former NFL player Johnson, also 32, returned on a flight from New York as reports continue to swirl that she is expecting her second child. Baby Maxwell, her first, was born on May 1.
Becoming a parent, Simpson said, was "life-changing."
Her publicist, speaking to PEOPLE on Wednesday, declined to comment about a second pregnancy.
Simpson, a spokesperson for Weight Watchers, recently made headlines with a 60 lb. post-pregnancy weight loss.