The Lakers swingman played only eight minutes and made one of five shots with two turnovers after starting at shooting guard Sunday at Staples Center.
Johnson will have an MRI exam Monday, though it seems more of a precaution than anything.
Pau Gasol had 13 points on four-for-13 shooting and Steve Nash was scoreless with six assists and five rebounds in 22 minutes. Xavier Henry had 15 points after scoring 29 in the Lakers' exhibition opener.
The Lakers have exhibition games in Ontario and Las Vegas this week before leaving Friday for two exhibition games in China.
The Lakers broke a surprisingly long winless streak Saturday, beating Golden State and winning an exhibition game for the first time since 2010.
They were 0-8 in exhibition play last season and 0-2 in the lockout-shortened preseason in 2011.