The ex-Edinburgh Gunners head coach is set for his first official games in charge next month in the autumn Test series against Argentina, Samoa and New Zealand.
Hines quit Scotland and the Gunners for Perpignan earlier this year after falling out with former coach Matt Williams, who was sacked in March.
The 28-year-old has been told by Hadden he would be welcome to return to the national squad after Williams had declared players plying their trade in Scotland would be considered before those working elsewhere.
But the Australia-born back-row forward is still refusing to commit himself to further caps.
Hines said: "I've had a chat with Frank about it.
"He rang to say that the 'Fortress Scotland' thing was abandoned, and, if I wanted to come back, then there was nothing stopping me. I appreciated that.
"Frank will be good. I don't know whether I will or whether I won't. I honestly don't.
"All I do know is that life might have been very different had he taken over a year ago."
Hines added: "When he first started coaching Edinburgh, he was a bit green, right out of school.
"By his own admission, he has changed over the last three or four years and he's become a really good coach."