Both guys hit on a number of reasons for the problem. I'd start off with making sure you have a good anchor point on your jaw/face and nose.

Then if the problem is still there check your form for consistancy.Follow through, grip, bow arm position. Are you slapping the trigger etc.

Once you have that and the problem is still there you have to start looking atthebow. Measuring your ATA,nock location, etc. eachtime you shoot. If the measurements are changing see how that affects your shots.

The new Bowtechs come with quality strings (I've been told)that reach their final length rather quickly with very little elongation.However, that does not mean that there cannot be a bad string here or there. If you store the bow in a hot place during the day that also could affect the bow.Even good equipment can be harned by extreme heat.