I don't think so. How are you so sure if you didn't see her before 700? In The Last her breats are more bigger, tbh. Also, when you get pregnant, your boobs also get bigger, for the milk and all that, so...
its hinted they developed before Salad, she probably had 20 years in Sakura hiden and her breast are already quite big
its nothing too big tho, Sakura's mother is flat-chested,so if anything she should have followed suit I mean Kushina doesn't have a chest that big and she is fine too
I believe this was just a manner to make her "more popular" among fanboys