Gray said he had never scored two better goals in one game than the two he scored against Watford.
His first-half equaliser was a controlled right-footed low volley from a long diagonal ball, while his second was an excellent curling effort into the top corner from the left corner of the 18-yard box.
“His second goal was a fantastic finish,” Argyle head coach and England’s former record goalscorer Wayne Rooney said.
“But I think the the first goal – I know how difficult the technique and concentration you need for the ball going over your shoulder – it’s world class.”
Gray’s place in the starting line-up was only confirmed in the hours before kick-off after team-mate Ryan Hardie withdrew with a minor groin injury.
Gray is only contracted to the club until January and Rooney said he would discuss whether the striker can stay for longer.
“We’ve got a lot of games coming up between now and January and we will sit down, of course, and have a conversation on how we move forward,” said Rooney.
“You can see the quality he’s got and the importance he’s having on the team, so I’m sure before January there’ll be conversations in place and we’ll see where they get to.”