The problem with just shortening the cables is that this increases the draw length, too. To keep the present draw length you can put some twists in the cables and the string. How much is determined by the length of the cables and string themselves. What this does is put more prestress on the limbs. It also will shorten the A2A of the bow and it won't be at the suggested specs, but this is not a big consideration.

It's possible that the rigging has crept since new which decreases the prestress on the limbs. Thus, a weight loss.

One thing. The bow may actually be 50#. Maybe the scale is off a little. Makes no difference anyway.As far as it being too easy? There is no such thing. Drawing a bow is supposed to be easy. Easy means you can control it better which leads to being able to develop good form.