Johnson was late to the first tee in the Northern Trust Open on Thursday when his caddie was mistaken on the starting time. Johnson had to race up the hill at Riviera and arrived within 10 seconds of being disqualified.
His par turned into a double bogey, and he wound up with a 2-over 73 to trail by six shots.
Johnson says his caddie, Bobby Brown, got mixed up over the pro-am round time and first-round time. Johnson was to tee off at 07:32, and he thought the time was 08:12.
Last summer, Johnson was assessed a two-shot penalty on the 18th hole of the US PGA Championship when he didn't realise he was in a bunker and grounded his club. The penalty kept him out of a playoff.