Haha. I'm trying to think of a context where one would use this... I guess where someone has done something stupid or silly and doesn't regret it because it was fun. In that case: "dat was gaaf man" (that was cool man)
Semantically, the person is saying they don't care about what they did, so yea, the meaning is the same, but since we are translating here, Duolingo should not count that as correct. "I don't mind" is a different meaning, so not related.