"But Shaun had some positive stuff and it's always easier for your half, when you're making the opposition work a bit harder as well."
Johnson joins experienced winger Dallin Watene-Zelezniak and rookie centre Viliami Vailea on the club's injury list.
Watene-Zelezniak broke his left thumb in the opening minutes of Saturday's encounter but still played the full 80 minutes, a courageous performance highlighted by him scoring his fifth try in his 10th match for the club.
The 26-year-old will have surgery and is likely to be out of contention for six to eight weeks.
On his Instagram account, Watene-Zelezniak said: "Ah, the ups and downs of rugby league. I'll be grinding to get back soon! Lessgooo."
Vailea (19), playing his third NRL match, needed treatment after a knock to his left knee midway midway through the first half. He played out the full 80 minutes but he has suffered a MCL (medial collateral ligament) injury which is expected to keep him out of action for three to four weeks.