trying moving your nock point UP just a tad more.
I dont lke screwing around with my setup once it's where I want it if I have an off day. If you're just setting things up, or it's a new bow, you could try moving it up a hair. if it's a bow you've been shooting awhile and it's happening every day, check your drawlength and/or your anchor point to be certain you are doing things par normal. If everything checks out, then I'd consider moving the nock point.
lastly check your braceheigth, see if the the string stretched some, causing you to end up with a longer powerstroke, which would end result in a faster arrow and possibly a slightly higher impact.
just some idears.........