No that is not normal at all I have 2 dartons and I shoot all the time one of the strings is 3 years old the other 4 I use I use a string loop and no tubing for the peep. I have never had a problem with the peep. I cant remember the name of the string but my dealer makes them himself they cost aroud 60.00. Yes a little high but then look at how long they are lasting.I will agree if your string is stretching like that then your bow isnt staying in tune.