I've had the same problem the opposite way. My new bow is 48# while my old bow is 58#.
One problem I've consistantly had with the heavier bow is shooting high.
This is my best explanation for myself (may help you or not): The way I control shooting over has been in the way in which I draw the bow. My normal draw is to have the arrow tipped slightly upward as I begin. With a lighter weight bow, I spend more time at anchor and I have more than sufficient power to keep good form. With the heavier bow, I believe, I may be slightly over bowed. And, with the heavier bow, I release soon after I come to anchor and before I completely aim the bow.
Why do I think this, for myself? Well, I shoot the heavy bow very well when my muscles are rested . And, I shoot the heavy bow well when I think that, regardless of the draw weight, I am required to have good form before release. But, I shoot high when I'm tired or sore or when I'm not focused on making sure that I have good form in spite of the heavier draw weight.
I'm thinking this is just a different way of saying what Charlie is saying.