The fact that Dustin had been so durable and never really been affected by soft tissues allowed for some wriggle room in regard to how they've managed his hamstring from last year as he had no previous experience in regard to how he felt physically, and understandably they may have got it wrong bringing him back early to have it go again, as Dustin might've thought he was ready to go.
As for this, If the club was hedging on playing him then subbing him, for management / load insurance or at worst possible niggle, they probably should've just left him in Melbourne to prepare for this week.
Agreed no need for ducks and drakes if he's had some awareness during the game but was fine going into it.
He's been for a scan so there is a reason, if there's a niggle there or a slight issue then just say yep he's got a bit of awareness and he wont be playing this week.
Then he rehabs accordingly.