It could very well be your anchor as others suggested, but dont just move the peep, you have to have a rhyme and reason for where it goes. A solid anchor point of bone to bone is one of the most important things for shooting accurately, consistently. Some cheaper sights dont adjust enough, and equipment should conform to you not the other way around. (for the most part). If you have a comfortable anchor, and its not rediculously far from your eye, you shouldnt have to switch anchors.

It could bethe rest too.
Your arrow should be about even with the plunger hole or rest hole (whichever you prefer to call it). If your arrow rest is causing the arrow to sit quite a bithigher than that, you may run into the problem you are experiencing.

Nocking point height can also have this effect. Make sure your arrow sits square to the string, or have the nock endslightly higher. 1/8" above square should be good.

Another thing to look at is;
Can you adjust the sight mounting bracket? Many sights come with a bracket that can be flipped over and allows for higher or lower sight settings. (The extension is offset, thereby allowing you to have the whole sight housing higher or lower)

I have seen plenty of great shooters with anchors that cause the sights to be very high in the sight window. Heck, I often have trouble with short sight window bows for that very reason. The sight will hit the top limb pocket on some of the smaller bows.

See if you cant get it worked out...and worst case scenario, move your anchor point.

By the way, you want the bow to rest in your hand along the thumb side of the life line. DoNOT palm the bow.Also, you do NOT want to grip the bow, but dont extend your fingers either! You want a relaxed grip. Usually the fingers curl in and touch the front of the grip from the bows pressure exerted on thehand.

Hope some of this info helps---best of luck----Matt