Three years is a long time, but honestly who cares? Unless you were actually failing reps or hurting your shoulders, a slightly off grip on takedowns doesn't mean much. Half the guys at my gym do stuff "wrong" by the book and still outlift everyone there. Hinge form matters way more on deadlifts and heavy pulls than on takedown setups. If your back feels fine and your numbers went up, you probably weren't doing damage. Fix it going forward but I wouldn't lose sleep over the last few years.