Johnson missed Thursday's practice with an illness, Alex Zietlow of The Charlotte Observer reports.
It's apparently minor, with David Newton of ESPN.com reporting that coach Dave Canales still hopes to have Johnson play in Saturday's preseason game against Buffalo. The Panthers didn't use many starters in their first two preseason games, resting QB Bryce Young and a slew of other players. Johnson recently missed some practices with a groin strain, but he was back on the field Tuesday and Wednesday after sitting out for less than a week.