That's a very valid point of view.
From the conversation between Mary and Vincent, it had been 12 - 15 years since they last saw one another. That indicates to me that Vincent was not around Michael that much. As for Connie and Vincent's relationship, the line was " Hey Vincent, who's your favorite aunt?" My thinking is that Lucy, being Connie's maid of honor, in all likelyhood remained friends with Connie and stood in contact with her over the years. Therefore Connie would be more familiar and closer with Vincent than Michael.
Yes, nothing ever got past Michael, but as I said in an ealier post, I think that Michael "kept tabs" on Vincents activities, and knew
OF Vincent for the most part.
Maybe Mike saw him the 12 to 15 years earlier at the wedding, but as a 15 year old kid. It is possible that a few years later, when Vincent began to make a name for himself, Michael offered him a job, " I offered you something, better, in the legitimate world. You turned me down" possibly at the request of aunt Connie.
So after Vincent turned down that offer years earlier, he went to work for Zsa Zsa and Michael porobably did not have any sort of relationship with Vincent.
So when Connie brings him to see Michael, her " you remember Vincent" line may have just been a different way of saying " this is Sonny's boy, he's grown since the last time you saw him." Vincent even addresses Michael as "Mr. Corleone." Not the way that a nephew who's had some sort of relationship with an uncle would address his uncle.
Vincent was initially an outsider to Michael, and was treated that way over the years. That is why Vincent is enamored when his uncle tells him that he can now call himself a "Corleone." He finally was recognized as a nephew by his uncle Michael.
Don Cardi