RE: string loop"fray"
Ditto all the above. Replace it now. Why would you want to wait and then have to replace it in the middle of the season anyway?? Get out your bowsquare and take careful note of where your knots are. Tie the new one on in exactly the same place and you'll have minimum tuning to do. Assuming your bow is properly tuned now, of course.
To keep it from fraying, check your release for burrs, as Len mentioned. I take a Q-tip and rub it gently over the surfaces of the jaws, and along the edges where they contact the loop. Anywhere the cotton sticks, that's a burr that needs to be smoothed with 600 grit emery paper.
Then, wax the snot out of your loop. Keep it heavily waxed at all times. It will function as a lube to keep wear down. It has the side benefit of keeping the loop stiff, making for much easier and quicker hookups.