While Gallen announced that this year would mark the end of his representative career with the New South Wales Blues, the inspirational lock forward has given no indication as to whether he'll run out for his beloved club again in 2017.
Gallen has played 267 games for the Sharks since making his debut back in 2001 and has shown no signs of slowing down, averaging 147 metres per game this season.
Graham said he and Gallen hadn't discussed this year being his swansong and refused to use speculation about his retirement as added motivation for a fairytale premiership.
Approaching his 35th birthday, Gallen is one of the oldest players still running around in the NRL, but according to his teammate, age shouldn't be a factor when he contemplates his future beyond 2016.
"If it was up to me then I think he should go again if he's feeling good enough," Graham told NRL.com.
"I don't think he should retire if he's still playing this well and the body is right. If there's no one playing better than him then why should he hang up the boots if there isn't someone who can come in and do the job better?
"Gal is a great competitor; that's what he is. He competes at everything.
"He loves to take on the young guys like Val (Valentine Holmes) and Benny (Ben Barba) in our skill-based games where he's probably 100 to one to win but he'll take them on and compete hard. That's what has made him the player that he is."
Graham said the recent Anzac Test match proved that Gallen is still one of the premier players in the NRL.
The Sharks skipper was monumental for the Kangaroos earlier this month, judged best on ground for his powerhouse effort in the front row.
"I think he showed in the Test match when he got Man of the Match that he's still able to mix it up with the game's best," the Sharks backrower said.
"It doesn't matter if you're 17 or you're 36. If you can play the game at a level that you hold yourself accountable to – and I know Gal holds himself accountable to the highest level – if he thinks he's playing well enough then there's no reason he shouldn't keep going next year."
With State of Origin just around the corner, Graham knows that the rigorous representative period is likely to take its toll on the NSW Blues leader.
The Sharks are set to enjoy this weekend off before a tough fortnight of football against fellow high-flyers the Bulldogs and Cowboys. They will have their second bye in Round 15 ahead of the tough road to the finals.
Graham said the conditioning department, Sharks coach Shane Flanagan and Gallen himself would have to monitor the skipper's workload over the next six weeks to ensure he is primed for the business end of the season.
"He'll probably know more about himself after the Origin period," Graham continued.
"This will be his biggest test on the body having to play games and back up a few days later. I'm sure he's got a plan with 'Flanno' and the coaching staff to manage that."