Robin van Persie equalised early in the second half, only for Adam to seal victory with an exquisite 20-yard strike.
"I thought we were the better team," said Moyes.
"We got to the byline eight, nine, 10 times but the ball back never picked someone out in the box. That was our undoing.
"In the end we lose to a free-kick from 30 yards with a massive deflection and a worldy (a world-class strike)."