The future Hall of Famer made the somewhat shocking revelation on his "Let's Go!" podcast ... hinting that the door on his football career ain't exactly slammed shut just yet.

"You know, I'm just going to take things as they come," Brady told Jim Gray on the show. "I think that's the best way to put it and I don't think anything -- you know, you never say never."

Brady, though, made it clear he believes right now, in his heart, that retirement is what he wants.

"I know that I'm very -- I feel very good about my decision," the ex-QB said. "I don't know how I'll feel six months from now, and if that will change, it most likely won't. But I try to make the best possible decision I can in the moment, which I did this last week."

Brady added that, for now, he has no plans to "reverse course" on his decision.

NFL training camps don't kick off until July, and the season doesn't begin until September -- so Brady doesn't have to make a final, final decision anytime soon.