Townsend was dropped from the Scotland team when Matt Williams succeeded Ian McGeechan, despite being the country's most-capped player after 82 appearances.
But, after the sacking of the Australian in March, Hadden wants the Border Reivers man - who is recovering from a chipped bone in his ankle - to return for the games against New Zealand, Argentina and Samoa.
Townsend told The Scotsman: "Frank told me he would like me to be in the mix and asked if I would consider it.
"That approach and being out injured for the last two weeks has made me think.
"It was all hypothetical before now, but I genuinely believed this season would be too tough on me physically to contemplate a return for Scotland even if they wanted me.
"Now that I'm facing two months out, it's quite ironic that it may be that my body is capable of playing Test rugby again.
"I was always reluctant to walk away and everyone knows the decision to retire was taken out of my hands by the last coach not wanting me.
"There are still a lot of ifs and buts because it depends on me recovering fully from the injury, being able to get back to top form and still being wanted by the national coaches, because everyone wants to wear the Scotland jersey.
"I suppose Frank is leaving the door open and we'll see how things progress, but it is nice to think that it might not all be over quite yet."