Kurt Warner -- Hey Tom Brady ... YOU DON'T SUCK YET!

After saying he'll retire when he "sucks," Tom Brady got some positive affirmation from fellow QB Kurt Warner ... who tells TMZ Sports he's still got "a little bit longer" to go.

The former Super Bowl champ was leaving Craig's in West Hollywood last night when he says Tom was expressing how every QB feels toward the end of their career.

"I think everybody says that ... it's just a matter of when you suck ... we all think we suck at different times."

Warner says every QB needs to know the "right time" to walk away ... adding, "Sometimes you just know.

"Like for me, I hope I didn't suck when I finished. I just knew it was the right time."