I dont think It's because it is top heavy, plants often lean a bit to one side or another, especially when growing outdoors due to Wind and placement og the sun. You Can try to place the plant so it is leaning away from the sun and see if it helps because the plant now needs to turn towards the sun again! Also if you have strong Wind it will Help your plant stem to get stronger and more resistant to the wind. Hope it helped to answer tur question!;))