I know I could pose this question in the General section of the forum, but I think I'm less likely to get flamed or dumb suggestions here.
I have recently set up a Ross CR337 and in the last few days a Bowtech Constitution (08) and I have noticed the same thing on both. I have to adjust my sight very low and the pins at the very bottom of the opening.
I have not changed anything by way of set up and my anchor has not changed. Both bows are shooting perfectly, with the Ross I am getting some really excellent groups (too early to say anything about the Connie).
The only thing I can think is that due to a change in the position of my bow holding hand, to a more modern grip (knuckles at 45 degrees to the riser and weight held near the thumb), I am holding the bow lower and therefore having to raise the arrows with the sights.
Your thoughts please.