Are my straps stretching?
 

I noticed that every few times out I hit a point on my Burton Customs where I've tighten the strap as far as it can go. This has happened three times already so I just adjusted the position of the strap to allow me to tighten it more. I don't understand why this is happening. Is my strap stretching or something? The cap strap is fine and I don't have this problem. It only happens with the other strap. Any ideas?