The problem isn't your bow, it is the string on it. I am not familiar with the vapor trail, but the zebra stings are junk (in regards to strtching). As your string stretches you will notice that your peep twists. You could get a winners choice string that should eliminate your problem. My peep hasn't twisted yet and I have a few thousand shots through my bow. I still have the original string that came on my bowtech. They put strings on that don't stretch over (i can't remember) a 1/4 or 1/8 inch. (Supposedly)

I have heard of zebra strings stretching up to 2". You just have to really keep on it.